Downhole apparatus and method

ABSTRACT

A downhole tool (32) comprises a tool housing (34) defining a central bore (35) and including a fluid port (20), and a valve member (40) mounted within the housing (34) and being movable from a closed position in which the fluid port (20) is blocked to an open position in which the fluid port (20) is opened. The tool (32) further comprises a catching arrangement (41) mounted within the housing (34) and comprising one or more radially movable seat members (106), and being configurable from a free configuration in which the seat members (106) permit an object (48) to pass through the tool (32), to a catching configuration in which the seat members (106) catch an object (48) passing through the tool (32).

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. application Ser. No.14/610,510 filed Jan. 30, 2015, which is a continuation ofPCT/GB2013/052045 filed Jul. 31, 2013, which claims priority toGB1223191.6, which was filed Dec. 21, 2012, and GB1213574.5, which wasfiled Jul. 31, 2012. This application is also related to U.S.application Ser. No. 14/610,440 entitled “Downhole Apparatus andMethod,” which was filed concurrently herewith; U.S. application Ser.No. 14/610,483 entitled “Downhole Apparatus and Method,” which was filedconcurrently herewith; and U.S. application Ser. No. 14/610,550 entitled“Downhole Apparatus and Method,” which was filed concurrently herewith.Each of the foregoing applications is hereby incorporated by referencein its entirety.

FIELD OF THE INVENTION

The present invention relates to downhole tools and methods, includingmechanically actuated downhole tools and methods. In particular, but notexclusively, the present invention relates to downhole tools and methodsassociated with well fracturing.

BACKGROUND TO THE INVENTION

There are many situations in which downhole tools must be selectivelyactuated. For instance, during hydraulic fracturing of a multiple zonewell, one or more tools are provided at each zone, and each tool needsto be actuated so that fluid is diverted to flow outwards to fracturethe surrounding formation. It is often desirable for the actuation to beperformed in a sequential manner to allow the formation to beprogressively fractured along the length of the bore, without leakingfracture fluid out through previously fractured regions.

The most common approach to tool actuation is still fully mechanical.Typically, balls of ever increasing size are dropped down the well bore.The balls pass though the first and intermediate tools, which have avalve seat larger than the ball, until they reach a tool in the wellwith an appropriate size of valve seat. The ball then seats at the toolto block the main passage and cause transverse ports to open thusdiverting the fluid flow. However, the use of ever increasing ballsrequires ever decreasing seats, and in some cases the smaller seats maydefine significant flow restrictions, which is undesirable.

WO 2011/117601 and WO 2011/117602 each describe an improved system whichuses balls of a substantially similar size and a mechanical countingdevice associated with each tool. Each dropped ball causes themechanical counting device to linearly progress along the main bore in apredetermined number of discrete steps until reaching an actuation siteof the tool whereupon the tool is actuated. The mechanical countingdevice can be located at an appropriate position (number of steps fromthe actuation site) for each tool such that the downhole tools aresequentially actuatable. This system has been found to be highlyeffective.

In the oil and gas industry there is a significant drive to improve theeffectiveness and reliability of tools which are deployed and operatedin a downhole environment. This is to ensure that the tools operate atmaximum efficiency, have minimum risk of failure or imprecise operation,can be flexible according to operator requirements, and minimize anynecessary remedial action, associated time delays and costs.

SUMMARY OF THE INVENTION

Aspects of the present invention relate to a downhole actuator foractuating a downhole tool. Aspects of the present invention relate to adownhole tool, such as a downhole fracturing tool. Aspects of thepresent invention relate to a combination of a downhole actuator anddownhole tool. An aspect of the present invention relates to a catchingarrangement, for use in catching an object, such as a ball or dart.Further aspects of the present invention relate to methods of operatingdownhole actuators and tools, performing wellbore operations such asformation stimulation, fracturing, wellbore sealing, cementing, flowcontrol and the like. Further aspects of the present invention relate towellbore systems, such as completion systems, for example completionsystems which permit or facilitate formation stimulation to be achieved,such as fracturing operations and the like to be performed. Aspects ofthe present invention relate to methods of manufacturing downhole toolcomponents, such as a component for catching an object. Aspects of thepresent invention relate to an indexing sleeve for use in a downholeactuator. Aspects of the present invention relate to an inspectionapparatus for use in inspecting or determining the position of anindexing sleeve within a housing of a downhole actuator.

These and other aspects may include any combination of features aspresented below.

Embodiments of aspects of the present invention may be used in anydownhole operation, such as in formation stimulation operations, sealingoperations, flow control operations and the like.

A downhole actuator according to an aspect of the invention may comprisea housing and an indexing sleeve mounted within the housing. Theindexing sleeve may be operated to move in a number of discrete linearmovement steps along the housing towards an actuation site by passage ofa corresponding number of actuation objects.

Suitable actuation objects may include balls, darts, plugs, any otherobject dropped or otherwise passed into a wellbore or wellboreinfrastructure to perform a tool-actuation function, or any combinationof these. An actuation object may form part of or be provided incombination with the downhole actuator.

The indexing sleeve may be configured to temporarily capture a passingactuation object to permit the object to drive the indexing sleeve adiscrete movement step, and subsequently release the object uponcompletion of the discrete movement step.

The downhole actuator may be configured to permit the indexing sleeve tobecome disabled, such that an actuation object may pass through theactuator without causing the indexing sleeve to move. The indexingsleeve may become disabled by alignment, for example axial alignment, ofsaid indexing sleeve with a disable region within the housing.

The downhole actuator may be configured to permit the indexing sleeve tobecome disabled at an actuation site. Such an arrangement may permit theindexing sleeve to become disabled following or during actuation of anassociated tool, system, process or the like.

The downhole actuator may be configured to permit the indexing sleeve tobecome disabled at a location which is remote from an actuation site.Such an arrangement may permit the indexing sleeve to become disabled toprevent actuation of an associated tool, system, process or the like.

The indexing sleeve may comprise an engaging arrangement configured tobe engaged by an actuation object passing through the downhole actuatorto facilitate movement of the indexing sleeve. The indexing sleeve maybe disabled by configuring the engaging arrangement.

The downhole actuator may actuate a downhole tool. The downhole tool maycomprise an actuatable member.

The downhole tool may include any downhole tool, such as a valve,packer, inflow control device, choke, communication device, drillingassembly, pump, fracturing tool, catcher assembly, flow diverter or thelike, or any suitable combination of downhole tools.

The downhole tool may include a tool housing and a valve member which ismovable by the indexing sleeve. The valve member may be movable to opena fluid port, such as a fluid port in or through a wall of the toolhousing. The valve member may be movable axially to open a fluid port.The valve member may be movable rotationally to open a fluid port. Thevalve member may be movable both axially and rotationally to open afluid port.

The downhole tool may include a catching arrangement. The catchingarrangement may be configurable between a free configuration in which anactuation object may pass the catching arrangement, and a catchingconfiguration in which an actuation object is caught or captured by thecatching arrangement.

The catching arrangement may be operated by the downhole actuator. Forexample, the catching arrangement may be reconfigured to the catchingconfiguration by the downhole actuator.

The catching arrangement may be reconfigured to the catchingconfiguration by movement of the actuatable member of the downhole tool,for example movement of the valve member towards its open position.

The catching arrangement may be configured to release a previouslycaught object. The catching arrangement may be configured to release apreviously caught object by establishing a condition, such as a pressurecondition, flow condition or the like within the downhole tool. Thecatching arrangement may be configured to release a previously caughtobject by a change in flow direction, for example reverse flow throughthe downhole tool.

The catching arrangement may be configurable from its catchingconfiguration to a release configuration in which a caught object may bereleased.

The catching arrangement may be reconfigured to the releaseconfiguration by action of a caught object acting against the catchingarrangement.

The catching arrangement may be reconfigured to an intermediate releaseconfiguration, for example by action of a caught object acting againstthe catching arrangement. The catching arrangement may be reconfiguredfrom an intermediate release position to a release configuration by avariation I a downhole condition, for example a variation in pressure,flow rate, flow direction or the like.

When the catching arrangement is configured in a release configuration,the catching arrangement may permit an object to pass. In such anarrangement the release configuration of the catching arrangement mayalso define a free configuration.

An aspect of the present invention relates to a downhole actuator.

The downhole actuator may be suitable for use in actuating a downholetool, system and/or process.

The downhole actuator may actuate or operate a downhole tool. Thedownhole tool may comprise an actuatable member.

The downhole tool may include any downhole tool, such as a valve,packer, inflow control device, choke, communication device, drillingassembly, pump, fracturing tool, catcher assembly, flow diverter,by-pass tool or the like, or any suitable combination of downhole tools.

The downhole actuator may comprise a tubular housing which includes ordefines an indexing profile on an inner surface thereof. An indexingsleeve may be mounted within the housing and may be arranged toprogress, for example linearly progress, through or within the housingtowards an actuation site in a predetermined number of discrete steps ofmovement, for example linear movement, by passage of a correspondingnumber of actuation objects through a central bore of the indexingsleeve.

The indexing sleeve may be arranged such that a final discrete step oflinear movement positions said sleeve at the actuation site. Theindexing sleeve may be arranged such that a final discrete step oflinear movement of the indexing sleeve permits said sleeve to actuate,or at least initiate actuation of, an associated downhole tool.

In use, a required number of actuation objects may be passed through theindexing sleeve to cause said indexing sleeve to move in a correspondingnumber of discrete steps towards the actuation site, to facilitateactuation of an associated downhole tool. In such an arrangementactuation of an associated downhole tool may at least be initiated uponthe indexing sleeve reaching the actuation site.

An associated downhole tool may be completely actuated upon the indexingsleeve reaching the actuation site.

In some embodiments an associated downhole tool may be partiallyactuated upon the indexing sleeve reaching the actuation site. Suchpartial actuation may comprise preparing an associated downhole tool tobe subsequently actuated. In such an embodiment, actuation of anassociated tool may be subsequently achieved or completed by analternative or associated actuation arrangement. Such an alternative orassociated actuation arrangement may be operated by an actuation object.Such an actuation object may include an actuation object which has alsomoved the indexing sleeve a discrete step towards the actuation site.Such an actuation object may include an actuation object which has alsomoved the indexing sleeve a final discrete step towards the actuationsite. In one embodiment an alternative or associated actuationarrangement may be operated by an actuation object which has also movedthe indexing sleeve a final discrete step towards the actuation site. Assuch, the actuation object may complete movement of the indexing sleevetowards the actuation site and then subsequently operate an alternativeor associated actuation arrangement for performing or completingactuation or operation of an associated downhole tool.

In an alternative embodiment a different actuation object from thatwhich has moved the indexing sleeve a discrete step may be used toactuate or complete actuation of an associated downhole tool. Theindexing sleeve may be configured to be positioned at the actuation siteby passage of n actuation objects, wherein an associate downhole toolmay be actuated by passage of n+m actuation objects, wherein m is anypositive integer.

Causing the indexing sleeve to move in one or more discrete steps ofmovement may permit the downhole actuator, and associated downhole tool,to be used as part of a downhole system, in which one or more actuationobjects are used in combination with other downhole actuators or tools.In some embodiments such a downhole system may include, for example,between 2 and 150, or more, downhole actuators or tools. Such actuatorsor tools may be operated in any desired sequence. Further, in such asystem different downhole tools may be actuated, in a desired sequence,by the downhole actuators.

The indexing sleeve may comprise an engaging arrangement configured tocooperate with the indexing profile of the housing to be engaged by anactuation object passing through the central bore of the indexing sleeveto drive the indexing sleeve one discrete step.

The engaging arrangement may comprise at least one engagement memberwhich cooperate with the indexing profile of the housing to be engagedby an actuation object passing through the central bore of the indexingsleeve to drive the indexing sleeve one discrete step.

The engaging arrangement may comprise first and second axially spacedengagement members which cooperate with the indexing profile of thehousing to be engaged by an actuation object passing through the centralbore of the indexing sleeve to drive the indexing sleeve one discretestep. The engagement members may define engagement protrusions.

At least one of the first and second engagement members may be engagedby an actuation object passing through the central bore of the indexingsleeve to drive the indexing sleeve one discrete step. In someembodiments both of the first and second engagement members may beengaged by an actuation object passing through the central bore of theindexing sleeve to drive the indexing sleeve one discrete step. In someembodiments the first and second engagement members may cooperate withthe indexing profile to be sequentially engaged by an actuation objectpassing through the central bore of the indexing sleeve to drive theindexing sleeve one discrete step.

The first and second engagement members may be arranged relative to eachother to permit only a single actuation object to be positionedtherebetween. This may assist to eliminate or reduce the possibility ofan actuation object passing through the indexing sleeve without alsomoving the indexing sleeve a corresponding discrete movement step. Forexample, in the event of two actuation objects passing through theindexing sleeve in close proximity, for example in quick succession,only one will be permitted to be positioned between the first and secondengagement members during such passage. This may require a leadingactuation object to complete a discrete movement step of the indexingsleeve before a trailing actuation object may fully act on the indexingsleeve. Such an arrangement may assist to mitigate a circumstance inwhich an actuation object passes through an indexing sleeve withoutbeing registered, and thus without causing a discrete linear movementstep. Such a circumstance may cause difficulties, such as causingdownhole tools to be actuated out of a desired sequence, causing adisparity between the actual setting of the actuator and an operator'sunderstanding, which may be based only on the number of objectsdelivered downhole, and the like.

The relative arrangement between the first and second engagement membersmay be selected in accordance with an actuation object which is utilizedto actuate and move the indexing sleeve a discrete step through thehousing.

An actuation object may be delivered downhole from surface.

An actuation object may be driven towards and through a downholeactuator according to the invention by a pressure differential definedacross the actuation object. An actuation object may be driven towardsand through a downhole actuator according to the invention by its ownmomentum or kinetic energy resulting from it being entrained with afluid flow, such as fluid flow established by pumping equipment. Suchfluid flow may comprise a treating fluid, such as a fracturing fluid. Anactuation object may be driven towards and through a downhole actuatoraccording to the invention by the action of gravity.

The relative arrangement between the first and second engagement membersmay be related to at least the geometry of an actuation object. Therelative arrangement may be related to an axial separation of the firstand second engagement members. The axial separation of the first andsecond engagement members may be less than or equal to twice the width,for example diameter, of an actuation object.

The relative arrangement may be related to a permitted radially inwardmovement of the engagement members into the central bore. The axialspacing of the first and second engagement members may be inverselyrelated to a permitted radially inward movement. When an actuationobject comprises a ball, the axial spacing of the first and secondengagement members may substantially correspond to a chord of alongitudinally extending cross section of the ball in which the twopoints of the chord correspond to a predetermined radially inwardextension.

In some embodiments the downhole actuator may define a counting deviceor apparatus, specifically a mechanical counting device or apparatus.That is, the downhole actuator may reflect the number of actuationobjects which have passed based on the position, for example linearposition, of the indexing sleeve along the housing. The downholeactuator may facilitate actuation of an associated downhole tool uponpassage of the desired or predetermined number of actuation objects.Preventing the passage of an actuation object without also registering acount by moving the indexing sleeve a corresponding discrete movementstep may allow the apparatus to very accurately reflect the number ofactuation objects which have passed. This may provide a number ofadvantages, such as preventing any early or late actuation of anassociated tool, providing an operator with confidence in theirunderstanding of the configuration of the actuator and associated toolat any time, and the like.

The engagement members may be configured or arranged to be sequentiallyengaged by a passing actuation object. In this arrangement theengagement members may be defined as upstream and downstream engagementmembers relative to the direction of travel of a passing actuationobject. As such, in use, cooperation with the indexing profile of thehousing may permit an actuation object to first engage the upstreamengagement member, and then continue to engage the downstream engagementmember, to drive the indexing sleeve one discrete step. In such anarrangement, the upstream and downstream engagement members may bedefined in relation to the direction of travel of an actuation object.That is, the direction of travel of an actuation object may be definedas a downstream direction.

Additionally, or alternatively, the indexing sleeve may cooperate withthe indexing profile of the housing to be moved in a discrete step inany direction of travel of a passing actuation object. As such, theindexing sleeve may be permitted to be driven in reverse directions bydiscrete linear movement steps, depending on the direction of travel ofan actuation object. As such, the indexing sleeve may be configured tobe driven in a forward direction, and/or a reverse direction. In such anarrangement, the forward direction may include one of a downholedirection and an uphole direction, and a reverse direction may includethe other of a downhole direction and an uphole direction. Thisarrangement may permit one or more actuation objects to be reverseflowed through the downhole actuator following said one or more objectsbeing forward flowed through the tool, while registering correspondingreverse discrete movement steps or counts. Accordingly, the linearposition of the indexing sleeve within the housing may continuouslyreflect the number and direction of passing actuation objects.

Reverse flow may be achieved by production of fluids from a subterraneanreservoir. Alternatively, or additionally, reverse flow may be achievedby reverse circulation of fluid within an associated wellbore. Forexample, reverse flow may be achieved by circulating fluid through anannulus defined between the downhole actuator and a wall of a bore holeor tubing within which the downhole actuator is located, andsubsequently through the housing of the actuator.

Reverse flow may be established to reposition the indexing sleeve in adesired location within the housing, for example to reset the downholeactuator or the like. Such an arrangement may permit in situ resettingof the indexing sleeve within the actuator.

Reverse flow may be established to move the indexing sleeve towards analternative actuation site, for example to initiate actuation of adifferent associated downhole tool. In such an arrangement the actuatormay be associated with two downhole tools on opposing axial sidesthereof, wherein the indexing sleeve may be driven in any desireddirection to initiation actuation of any one, or both, of the associateddownhole tools.

Reverse flow may be present or established in the event of a blockage.For example, reverse flow may be established to remedy a blockage withinthe downhole actuator, an associated downhole tool, or an associateddownhole system.

Reverse flow may be established to return objects to surface.

The indexing sleeve may be reconfigurable, in situ, to permit sequentialengagement of the engagement members in reverse directions of a passingactuation object. Such in situ reconfiguration may be achieved by aninitial passage of an actuation object.

The indexing sleeve may be arranged, for example during commissioning,to accommodate passage of an actuation object in a first direction, suchthat said object may sequentially engage the first and second engagementmembers and move the indexing sleeve a discrete step in said firstdirection. When in such an arrangement initial passage of an actuationobject in a second, reverse direction, may reconfigure the indexingsleeve such that passage of a further actuation object in the seconddirection may sequentially engage the engagement members in this seconddirection. During such reconfiguration, the actuation object initiallypassing in the second direction may engage only one of the first andsecond engagement members to move the indexing sleeve a requireddistance in the second direction to reconfigure the engagement membersby cooperation with the indexing profile and allow subsequent sequentialengagement by a further actuation object in the second direction. Theactuation object initially passing in the second direction may drive theindexing sleeve an equivalent discrete movement step.

The indexing sleeve may be formed of a unitary component. Alternatively,the indexing sleeve may be formed from multiple components andappropriately assembled or arranged together.

The first and second engagement members may define a confinement regiontherebetween, for temporarily accommodating an actuation object duringpassage of said object through the indexing sleeve. The confinementregion may be configured to permit only a single actuation object to beaccommodated therein at any time.

The first and second engagement members may be arranged on the indexingsleeve to be selectively moved radially by cooperation with the indexingprofile on the housing during movement of the indexing sleeve throughthe housing. Such radial movement of the first and second engagementmembers may selectively extend and retract said members relative to thecentral bore of the indexing sleeve. That is, the engagement members maybe moved radially outwardly to be radially extended from the centralbore, and moved radially inwardly to be radially retracted into thecentral bore. This arrangement may permit the engagement members to beselectively presented into a path of travel of an actuation objectthrough the central bore of the indexing sleeve to allow said sleeve tobe driven through the housing by one discrete step. Such radial movementof the first and second engagement members may sequentially present saidmembers into the central bore and a path of travel of an actuationobject to permit said object to sequentially engage the engagementmembers to drive the indexing sleeve through the housing by one discretestep.

The radial position of the first and second engagement members may becyclically varied by cooperation with the indexing profile duringmovement of the indexing sleeve through the housing. In particular, theradial position of the first and second engagement members may be variedover one full cycle during one discrete step of linear movement of theindexing sleeve. That is, at the end of a complete discrete movementstep each engagement member may return to a starting radial position, inpreparation for engagement by a subsequent passing actuation object.

In use, the first and second engagement members may cooperate with theindexing profile on the housing such that a passing actuation objectfirst engages one of the first and second engagement members, which maythus be defined as an upstream engagement member, to move the indexingsleeve a portion of a discrete linear step before entering a regionbetween the first and second engagement members, which may be defined bya confinement region, and then engaging the other of the first andsecond engagement members, which may thus be defined as a downstreamengagement member, to move the indexing sleeve a final portion of adiscrete linear step.

The radial position of the first and second engagement members may bevaried out of phase relative to each other by cooperation with theindexing profile during movement of the indexing sleeve through thehousing. That is, one of the engagement members may be positionedradially inwardly and thus radially retracted into the central bore,while the other engagement member may be positioned radially outwardlyand thus radially extended from the central bore, with the position ofeach member varying in an out of phase manner as the indexing sleevemoves linearly through the housing. Such an arrangement may permit thefirst and second engagement members to be sequentially engaged by anactuation object passing through the indexing sleeve. That is, in aninitial configuration one engagement member, which may be defined as anupstream engagement member, may be radially retracted into the centralbore, and the other engagement member, which may be defined as adownstream engagement member, may be radially extended from the centralbore. In such an arrangement, an actuation object may engage theupstream engagement member and initiate movement of the indexing sleeve,with cooperation of the engagement members with the indexing profileduring this initial movement causing the upstream engagement member tomove radially outwardly and the downstream member to move radiallyinwardly, thus allowing the actuation member to move past the upstreamengagement member and engage the downstream engagement member andcomplete the discrete movement step of the indexing sleeve.

One or both of the first and second engagement members may be mountedwithin a slot extending through a wall structure of the indexing sleeve.Such an arrangement may permit the engagement member to cooperate withthe indexing profile of the housing to be moved radially and becomeselectively extended and retracted relative to the central bore of theindexing sleeve.

One or both of the first and second engagement members may be biased ina preferred radial direction. In one embodiment one or both of the firstand second engagement members may be biased in a radially outwarddirection. In such an arrangement one or both of the first and secondengagement members may be biased in a direction to be retracted from thecentral bore of the indexing sleeve. Such a bias may function to retainthe indexing sleeve at a set position relative to the housing in theabsence of a passing actuation object.

One or both of the first and second engagement members may be mounted ona respective finger provided as part of the engaging arrangement of theindexing sleeve. The finger may define a collet finger, such that theindexing sleeve may define a collet sleeve. The finger may be deformableto permit appropriate radial movement of the associated engagementmember upon cooperation with the indexing profile. The finger may beresiliently deformable to provide a desired bias. A proximal end of thefinger may be secured, for example by integrally forming, with theindexing sleeve. A distal end of the finger may support, for example byintegrally forming, the associated engagement member.

An engagement member may be of a greater radial thickness than anassociated finger. That is, an engagement member by define a greaterradial dimension than an associated finger.

The finger may extend longitudinally relative to the indexing sleeve. Insome embodiments the finger may extend circumferentially relative to theindexing sleeve.

The finger may define a tapering thickness, for example radialthickness. Such a tapering thickness may assist to control stress and/orstrain within the finger. For example, such a tapering thickness mayassist to provide uniform stress distribution within the finger duringdeformation thereof. Further, such a tapering thickness may permit thefinger to bend more uniformly along its length, rather than focusingdeformation at a discrete location.

In some embodiments the thickness of the finger may taper from one endof the finger to an opposite end. The thickness may taper from a root ofthe finger to a tip of the finger.

The thickness of the finger may taper in a linear manner. The thicknessof the finger may taper in a non-liner, such as a curved, manner.

The finger may define a constant width, for example circumferentialwidth.

The finger may be contained within a slot formed in a wall structure ofthe indexing sleeve.

In one embodiment the indexing sleeve may comprise first and secondfingers which support a respective one of the first and secondengagement members.

The first and second fingers may extend in a common direction. In thisarrangement the first and second fingers may be arrangedcircumferentially relative to each other. In such an arrangement thefirst and second fingers may overlap in an axial direction.

The first and second fingers may extend in opposing directions. In oneembodiment respective distal ends of the first and second fingers may bepositioned adjacent each other. In alternative embodiments respectiveproximal ends of the first and second fingers may be positioned adjacenteach other.

The engaging arrangement may comprise an array of first engagementmembers. The array of first engagement members may be arrangedcircumferentially. The array of first engagement members may be evenlycircumferentially distributed. Alternatively, the array of firstengagement members may be unevenly distributed. The array of firstengagement members may be manipulated collectively, for examplesimultaneously, by cooperation with the indexing profile of the housing.Each first engagement member may be mounted on a respective firstfinger.

The array of first engagement members may define gaps therebetween. Thatis, adjacent first engagement members may define a gap therebetween. Thearray of first engagement members may define gaps therebetween when saidfirst engagement members are positioned radially inwardly to be engagedby an actuation object. Such gaps may facilitate fluid transfer betweenthe individual first engagement members. This may permit a degree offluid bypass even when an actuation object is engaged with or againstthe first engagement members. Such fluid bypass may allow fluid tocontinue to circulate through the actuator even during passage of anactuation object. This may facilitate swift translation of an actuationobject through the actuator. This may provide advantages in terms ofallowing an actuation object to swiftly move through a downholeactuator, and subsequently onward to another downhole actuator or othertool for further actuation purposes.

In an alternative embodiment the array of first engagement members maybe configured to be positioned in close proximity to each other, orengaged with each other, at least when the first engagement members arepositioned radially inwardly to be engaged by an actuation object. Thatis, adjacent first engagement members may be configured to be engaged orpositioned in close proximity. Such an arrangement may minimize fluidpassage between individual first engagement members, for example when anactuation object is engaged with the first engagement members. Such anarrangement may provide a degree of sealing, which may permit a pressuredifferential to be established across an actuation object when engagedwith the first seat members, to permit said actuation object to drivethe indexing sleeve.

In some embodiments the housing may define an outer diameter in theregion of 114.3 mm (4.5″), and the engagement arrangement may compriseeight (8) first engagement members. In such an embodiment the engagementmembers may be distributed around the indexing sleeve such that twoengagement members are provided in each quadrant of the indexing sleeve.

In an alternative embodiment the housing may define an outer diameter inthe region of 139.7 mm (5.5″), and the engagement arrangement maycomprise twelve (12) first engagement members. In such an embodiment theengagement members may be distributed around the indexing sleeve suchthat three engagement members are provided in each quadrant of theindexing sleeve.

The engaging arrangement may comprise an array of second engagementmembers. The array of second engagement members may be arrangedcircumferentially. The array of second engagement members may be evenlycircumferentially distributed. Alternatively, the array of secondengagement members may be unevenly distributed. The array of secondengagement members may be manipulated collectively, for examplesimultaneously, by cooperation with the indexing profile of the housing.Each second engagement member may be mounted on a respective secondfinger.

The array of second engagement members may define gaps therebetween.That is, adjacent second engagement members may define a gaptherebetween. The array of second engagement members may define gapstherebetween when said second engagement members are positioned radiallyinwardly to be engaged by an actuation object. Such gaps may facilitatefluid transfer between the individual second engagement members. Thismay permit a degree of fluid bypass even when an actuation object isengaged with or against the second engagement members. Such fluid bypassmay allow fluid to continue to circulate through the actuator evenduring passage of an actuation object. This may facilitate swifttranslation of an actuation object through the actuator.

In an alternative embodiment the array of second engagement members maybe configured to be positioned in close proximity to each other, orengaged with each other, at least when the second engagement members arepositioned radially inwardly to be engaged by an actuation object. Thatis, adjacent second engagement members may be configured to be engagedor positioned in close proximity. Such an arrangement may minimize fluidpassage between individual second engagement members, for example whenan actuation object is engaged with the second engagement members. Suchan arrangement may provide a degree of sealing, which may permit apressure differential to be established across an actuation object whenengaged with the second seat members, to permit said actuation object todrive the indexing sleeve.

In some embodiments the housing may define an outer diameter in theregion of 114.3 mm (4.5″), and the engagement arrangement may compriseeight (8) second engagement members. In such an embodiment theengagement members may be distributed around the indexing sleeve suchthat two engagement members are provided in each quadrant of theindexing sleeve.

In an alternative embodiment the housing may define an outer diameter inthe region of 139.7 mm (5.5″), and the engagement arrangement maycomprise twelve (12) second engagement members. In such an embodimentthe engagement members may be distributed around the indexing sleevesuch that three engagement members are provided in each quadrant of theindexing sleeve.

In some embodiments the array of first engagement members may definegaps therebetween, and the array of second engagement members may alsodefine gaps therebetween. Such an arrangement may facilitate swiftpassage of an actuation object.

In some embodiments a flow rate of, for example, between 5 and 70barrels per minute may be provided to advance an actuation object. Theprovision of fluid bypass past the first and/or second engagementmembers may permit such flow rates to be substantially maintained duringpassage of an actuation object. For example, a flow rate of 15 to 50barrels per minute may be provided to advance an actuation object.

The first and second engagement members may each define a seatarrangement for allowing an actuation object to engage and seat againstduring passage through the indexing sleeve. An actuation object maydrive the indexing sleeve through the housing when engaged and seatedagainst a seat arrangement. The engagement members may define a seatarrangement on one axial side thereof. This may permit an actuationobject to engage and seat against the engagement members in a singledirection of movement. In some embodiments the engagement members maydefine a seat arrangement on opposing axial sides thereof. This maypermit an actuation object to engage and seat against the engagementmembers in reverse directions of movement.

One or both of the first and second engagement members may define a seatsurface to be engaged by an object. The seat surface may be arranged toprovide a substantially continuous or complete engagement with anobject.

The seat surface may be arranged to provide discontinuous or incompleteengagement with an object. Such an arrangement may permit non-sealingengagement to be achieved between the seat surface and an actuationobject, for example to permit flow by-pass. In one embodiment a seatsurface may comprise or define an axially extending slot or channel.

The seat surface may define a curved seat surface, such as a convex seatsurface. Such an arrangement may be provided in combination with use ofan actuation object having a curved, such as convex surface. Providing acurved seat surface, and in particular a convex seat surface, may assistto prevent or at least mitigate the swaging, jamming or otherwiselodging of an actuation object relative to the engagement members.

Providing a curved seat surface, and in particular a convex seat surfacemay permit a greater degree of control over the transmission of loadforces between an actuation object and the associated engagement member,when engaged, and to other components of, or operatively associatedwith, the indexing sleeve. For example, such greater control mayadvantageously permit a preferred transmission of forces from anactuation object and via the individual engagement members into theindexing profile of the housing. Such a preferred transmission may beselected to minimize bending moments, for example, on the indexingsleeve, such as on individual fingers which support the engagementmembers.

The indexing sleeve may be advanced along the housing in a discretemovement step by energy provided by the object, for example kineticenergy.

The indexing sleeve may be advanced along the housing in a discretemovement step by impact of an actuation object against one or both ofthe first and second engagement members, for example sequential impactagainst the first and second engagement members. Such an arrangement mayutilize the momentum of a passing actuation object to advance theindexing sleeve. This may permit the indexing sleeve to be driven by arelatively rapid advancement of an actuation object through said sleeve.Further, relying on an impact force of an actuation object against thefirst and second engagement members to advance the indexing sleeve maynot necessarily require a fluid seal to be achieved between the objectand the respective engagement members. In some embodiments, one or bothof the first and second engagement members may be configured to providea degree of fluid bypass when engaged by an actuation object, tofacilitate substantially continuous flow through the downhole actuator,which may assist with rapid or swift translation of an actuation object,and corresponding rapid operation of the downhole apparatus. Such rapidtranslation of an actuation object may provide advantages in systems inwhich the actuation object is used to operate multiple actuators and/ortools.

The use of an impact force to advance the indexing sleeve may facilitatemonitoring of the position of the indexing sleeve from a remotelocation. For example, impact of an actuation object against theengagement members may create an acoustic signal, which may be monitoredfrom a remote location.

In some embodiments, although sealing may not be necessary between anobject and the respective engagement members, a certain degree of flowrestriction may be created during engagement with an object with theengagement members, which may create a variation in the pressure of afluid flowing within the downhole actuator, for example a fluid used todrive the object through the downhole actuator. In some embodiments sucha variation in pressure may facilitate monitoring from a remotelocation, by monitoring the variation in pressure.

In some embodiments the indexing sleeve may be advanced along thehousing in a discrete step by a differential pressure applied betweenupstream and downstream sides of the indexing sleeve. Such adifferential pressure may be created upon engagement of the object witheach of the first and second engagement members. In one embodiment anactuation object may sequentially sealingly engage the first and secondengagement members to facilitate creation of a differential pressure.Alternatively, an actuation object may sequentially engage the first andsecond engagement members to create a flow restriction and thus create aback pressure. Such a flow restriction may be provided between or arounda point of contact of an actuation object and an engagement member.Alternatively, or additionally, such a flow restriction may be providedbetween the indexer and the housing when an actuation object is engagedwith an engaging member.

The use of a differential pressure to advance the indexing sleeve maypermit monitoring of the downhole actuator to be achieved from a remotelocation, for example by monitoring a variation in pressure andassociating this variation with appropriate engagement of an actuatorobject with the engagement members. For example, upon and duringengagement of an actuation object with an engagement member a pressureincrease or spike may occur upstream of the object. This pressureincrease may function to drive the actuation object and indexing sleevewithin the housing. When an actuation object is released or is permittedto pass an engagement member, pressure may fall. Such a pressurevariation may permit an operator to obtain an understanding of theprogress of an actuation object.

In some embodiments the downhole actuator may be provided with or incombination with a monitoring apparatus or system, such as an acousticmonitoring apparatus or system, pressure monitoring apparatus or system,flow rate monitoring apparatus or system or the like.

The downhole actuator may comprise an anti-rotation arrangement providedbetween the indexing sleeve and the housing. The anti-rotationarrangement may comprise a key and key-way arrangement. In oneembodiment the indexing sleeve may comprise one or more keys, such aslongitudinal ribs, and the housing may comprise a key-way, such as alongitudinal slot configured to receive a key. Such an arrangement maypermit relative longitudinal movement of the indexing sleeve through thehousing, while preventing relative rotational movement.

The indexing sleeve may comprise a key provided, for example byintegrally forming, on an outer surface of a wall structure betweenadjacent slots which contain circumferentially adjacent engagementmembers.

The anti-rotation arrangement may permit a milling operation to beperformed on the indexing sleeve, for example to mill through theindexing sleeve as part of a remedial operation.

The downhole actuator may comprise a stand-off arrangement radiallypositioned between the tubular housing and the indexing sleeve. Thestand-off arrangement may be configured to define a radial separationgap between the housing and the indexing sleeve. The stand-offarrangement may provide such a radial separation gap during movement ofthe indexing sleeve relative to the housing.

The radial separation gap may be provided to assist in preventingbinding of the indexing sleeve within the housing, for example bydebris, such as proppant material, adversely accumulating or becomingtrapped between the housing and indexing sleeve.

The width of the radial separation gap may be provided at a preferredminimum gap width. Such a preferred minimum gap width may be selected inaccordance with a fluid being communicated through the tool. In oneembodiment a preferred minimum gap width may be defined or selected inaccordance with the dimension of a particle or particles, such asproppant, being carried by a fluid communicated through the actuator. Insuch an arrangement the minimum gap width may be selected in accordancewith the inability of individual particles to bridge the radial gapbetween the housing and the indexing sleeve.

In one embodiment the preferred minimum radial gap width between thehousing and indexing sleeve may be defined in accordance with a meandimension of particles, such as proppant, being carried by a fluidcommunicated through the tool. A preferred minimum gap width may beselected to be in the region of 1 to 20 times the mean particlediameter, for example in the region of 1 to 10 times the mean particlediameter, such as between 1 to 5 times the mean particle diameter. Inone embodiment a preferred minimum gap width may be in the region or atleast twice the mean particle diameter.

The stand-off arrangement may permit the indexing sleeve to besubstantially concentrically positioned within the housing.

The stand-off arrangement may permit a substantially uniform gap to beprovided between the indexing sleeve and the housing, for example todefine a uniform annulus area.

The stand-off arrangement may comprise at least one rib positionedbetween the housing and the indexing sleeve.

The stand-off arrangement may comprise a plurality of circumferentiallyarranged ribs positioned between the housing and the indexing sleeve.

At least one rib may extend axially.

At least one rib may be provided on the indexing sleeve, for examplemounted on the sleeve, integrally formed with the sleeve or the like.

At least one rib may be provided on the housing, for example mounted onthe housing, integrally formed with the housing or the like.

At least one rib may define a v-shape profile at one or opposite axialends thereof. Such a profile may permit the rib to readily drive orplough throw debris or material which may be present between theindexing sleeve and the housing.

At least one rib may define a tapering thickness, such as a taperingradial thickness. Such an arrangement may improve material flow aroundthe at least one rib. The tapering thickness may define a ramp profile.One or both axial end regions of at least one rib may define a taperingthickness. The thickness may taper linearly, or alternativelynon-linearly.

The downhole actuator may permit the indexing sleeve to be disabled,such that the indexing sleeve, when disabled, may not be moved uponpassage of an actuation object. This arrangement may still allow anactuation object to pass through the indexing sleeve, for example foruse in a further downhole actuator and downhole tool. The indexingsleeve may be disabled in accordance with a relative positioning withinthe housing. In this respect, the indexing sleeve may be moved from anenabled configuration to a disabled configuration.

The downhole actuator may be configured such that the indexing sleevemay be disabled at the actuation site. As such, upon reaching theactuation site to actuate an associated downhole tool, the indexingsleeve may also become disabled. This may prevent any further movementof the indexing sleeve following performance of its actuation function.Permitting the indexing sleeve to become disabled at the actuation sitemay maintain an associated downhole tool in an actuated state. Forexample, the indexing sleeve may function as a latch.

The downhole actuator may be configured such that the indexing sleevemay be disabled at a location remote from the actuation site. Thisarrangement may permit the indexing sleeve to be disabled prior toactuation of an associated downhole tool. For example, in some casesalthough a downhole tool and actuator may be installed downhole, forexample as part of a completion, an operator may subsequently decidethat the tool should not be activated, and the ability to disable theindexing sleeve at a location remote from the actuation site may permitthis to be achieved. As such, the downhole actuator may provideadditional flexibility for an operator. The indexing sleeve may bedisabled at an uphole position relative to the actuation site.

In one embodiment the indexing profile may facilitate the indexingsleeve to become disabled. The indexing profile may comprise a disabledregion, wherein alignment of the indexing sleeve with the disabledregion of the indexing profile permits the indexing sleeve to becomedisabled.

The indexing profile may comprise a disabled region which coincides withthe actuation site of the actuator. As such, the indexing sleeve mayeventually be aligned with the disabled region by passage of anappropriate number of actuation objects through the indexing sleeve.

The indexing profile may comprise a disabled region which is remote fromthe actuation site. The indexing sleeve may be configured to be moved inan uphole direction to be moved towards the remote disabled region. Theindexing sleeve may be moved to this remote disabled region by physicalintervention, for example by use of a shifting tool or the like deployedinto the downhole actuator. The indexing sleeve may define a profile tofacilitate engagement by a shifting tool.

The indexing profile may define a disabled region at opposing axial endsof said indexing profile. As such, the indexing sleeve may be disabledwhen located at either end region of the indexing profile.

At least a portion of the indexing profile of the housing may be formedin the inner surface of said housing. At least a portion of the indexingprofile of the housing may be formed in an insert which is mountedwithin the housing.

The indexing profile may define a longitudinal variation in the innerdiameter of the housing.

The indexing profile of the housing may comprise a plurality of annularrecesses arranged longitudinally along the housing.

Each annular recess may define a location of increased inner diameter ofthe indexing region of the housing. An intermediate surface betweenadjacent annular recesses may define a location of reduced innerdiameter of the indexing region of the housing. Accordingly, thepresence of a plurality of annular recesses may provide a variation ofthe inner diameter along the length of the housing, such that movementof the indexing sleeve through the housing permits the radial positionof at least one engagement member, for example the first and secondengagement members, of the engaging arrangement to be accordinglyvaried, and thus permit appropriate engagement by a passing actuationobject.

During movement of the indexing sleeve longitudinally through thehousing each engagement member may be sequentially received withinadjacent annular recesses. When received within a recess an engagementmember may be positioned radially outwardly and extended from thecentral bore of the indexing sleeve. When positioned intermediateadjacent recesses an engagement member may be positioned radiallyinwardly and thus retracted into the central bore of the indexing sleeveand thus presented into a path of travel of an actuation object throughthe indexing sleeve. Accordingly, a passing actuation object may act onthe engagement members in accordance with cooperation of the engagementmembers with the annular recesses of the housing.

One or more annular recesses may comprise tapered or ramped sides toallow cooperation with the engagement members to move said engagementmembers radially upon linear movement of the indexing sleeve through thehousing. Such tapered or ramped sides may assist with transition of theengagement members between radially outward and inward positions as theindexing sleeve is moved linearly through the housing. One or moveannular recesses may define a ramp angle relative to a longitudinal axisof the housing. A ramp angle may be between 10 and 80 degrees, forexample between 25 and 55 degrees, such as around 45 degrees.

At least one pair of annular recesses may be arranged at a differentaxial spacing than the first and second engagement members. At least onepair of adjacent annular recesses may be arranged at a different axialspacing than the first and second engagement members. Such anarrangement may permit the first and second engagement members to bealternately, for example in an out of phase manner, moved radiallyoutwardly and inwardly during movement of the indexing sleeve throughthe housing.

The indexing profile may comprise multiple annular recesses arrangedlongitudinally along the housing at a common axial separation or pitch.Such an arrangement may permit an indexing sleeve to be moved in anumber of equal discrete steps of movement. The common axial separationor pitch may differ from the axial separation of the first and secondengagement members. In some embodiments a plurality of annular recessesmay be longitudinally arranged at a common separation pitch, wherein theaxial separation of the first and second engagement members differs fromthis separation pitch or an integer multiple of this separation pitch.

The indexing profile may comprise at least one pair of annular recesseswhich are arranged at an axial spacing which is equivalent to the axialspacing of the first and second engagement members. In such anarrangement appropriate positioning of the indexing sleeve within thehousing may permit both the first and second engagement members to besimultaneously positioned within a respective recess and thus positionedradially outwardly and extended from the central bore, thus effectivelydisabling the indexing sleeve.

One axial end region of the indexing profile may comprise a pair ofannular recesses provided at an axial spacing which is equivalent to theaxial spacing of the first and second engagement members. In such anarrangement, upon reaching the axial end region of the indexing profilethe indexing sleeve may become disabled. This axial end region maycomprise or define an actuation site. This axial end region may compriseor define an end region which is remote from an actuation site.

Opposing axial end regions of the indexing profile may comprise a pairof annular recesses with an axial spacing which corresponds to the axialspacing of the first and second engagement members of the indexingsleeve. Such an arrangement may permit the indexing sleeve to bedisabled upon location at either axial end region of the indexingprofile.

The indexing sleeve may be initially positioned, for example duringcommissioning, at any desired location along the indexing profile. Suchan initial position along the indexing profile may determine therequired number of actuation objects, and thus required discrete stepsof movement, to drive the indexing sleeve to the actuation site andactuate an associated downhole tool. Such ability to initially positionthe indexing sleeve at a desired position may permit improvedflexibility of the downhole actuator. In some embodiments suchflexibility may permit multiple downhole actuators to be provided aspart of an actuation system, in which multiple downhole tools must beactuated, for example in a desired sequence, by common actuationobjects. That is, the indexing sleeve of different downhole actuatorswithin a common system may be initially set to reach an actuation siteupon passage of a different number of actuation objects. Thisarrangement may provide advantages in many downhole operations. Forexample, in some well fracturing operations it may be desirable tosequentially fracture discrete regions along the length of a formation.As such, fracturing tools in different regions may be sequentiallyactuated by an associated downhole actuator which includes anappropriately set or positioned indexing sleeve. Further, in somewellbore operations different types of tool may require actuation atdifferent times. For example, in some embodiments one or more packersmay require to be actuated and set, prior to subsequent actuation of oneor more different tools, such as fracturing tools or the like.Appropriate positioning of individual indexing sleeves associated withthe various downhole tools may permit the desired actuation sequence tobe achieved.

The housing may be provided as a single component.

The housing may be modular. The housing may comprise multiple housingmodules connected together, for example by a threaded connection, tocollectively define the housing. Individual modules may define a portionof the indexing profile, such that when the individual modules areconnected together the entire indexing profile is formed. One or moreindividual modules may form part of a downhole tool.

Adjacent housing modules may be secured together such that an indexingprofile feature is defined at an interface therebetween. Adjacenthousing modules may each define a portion of a profile feature such thatwhen connected the complete profile feature is formed. Such anarrangement may assist to ensure that when individual modules areconnected together the complete indexing profile is arranged asoriginally desired, and the possibility of forming an incorrect profilegeometry is minimized.

In one embodiment adjacent housing modules may define a portion of anannular recess, such that when connected a complete annular recess maybe defined.

Adjacent housing modules may be configured to be connected together viamale and female connectors, typically threaded connectors.

A sealing arrangement may be provided between adjacent housing modules

The provision of a modular housing may permit the downhole actuator tobe readily modified according to a precise required use. Further, suchan arrangement may minimize the requirement for bespoke systems, and mayallow multiple specific situations to be accommodated with a basicinventory of individual modules. For example, one downhole actuator mayrequire an indexing profile which accommodates ten discrete movementsteps of an indexing sleeve, and another downhole actuator, which may bepart of the same downhole system, may require an indexing profile whichaccommodates fifteen discrete movement steps of an indexing sleeve. Insuch a case an inventory of housing modules each defining a portion ofan indexing profile with five discrete steps may permit each actuatorrequirement to be fulfilled. Of course, any specific system with adesired number of movement steps may be accommodated in this manner, incombination with an advantageous ability to initially position theindexing sleeve at any position within the housing.

Further aspects of the present invention relate to a kit of parts whichmay be assembled to provide a downhole actuator. The kit of parts maycomprise a plurality of housing modules which include connectors topermit connection of the modules together to define a housing with anindexing profile on an inner surface thereof for cooperation with anindexing sleeve mounted within the housing. The kit of parts may includean indexing sleeve. The kit of parts may include any other component,system or arrangement as defined herein.

The downhole actuator may permit inspection prior to running into awellbore to confirm the location of the indexing sleeve relative to theindexing profile of the housing. Such inspection may avoid or minimizethe risk of deploying an actuator which has the indexing sleeve locatedat an incorrect position. Also, where multiple downhole actuators are tobe installed as part of a common system, the ability to readily inspecteach actuator can minimize the risk of the actuators being deployed outof a desired sequence.

The downhole actuator may be provided in combination with an inspectionapparatus for determining or confirming an initial location of theindexing sleeve. An aspect of the present invention relates to such aninspection apparatus.

The inspection apparatus may comprise an inspection object mounted on anelongate member. In use, the inspection apparatus may be inserted intothe downhole actuator, for example from one end of the housing, untilthe inspection object engages the indexing sleeve and the elongatemember extends from the housing. When the inspection apparatus is inthis fully inserted position the apparatus may provide a user with areference, for example a visual reference, which permits the location ofthe indexing sleeve within the housing to be identified or determined.

The elongate member may comprise one or more user identifiablegraduations or markings, such as surface markings or the like. Suchmarkings may assist a user to determine the location of the indexingsleeve relative to the housing. For example, a marking aligned with areference feature on the housing, such as a terminating end of thehousing, may allow a user to determine the relative location of theindexing sleeve.

The elongate member may be composed of a single component.Alternatively, the elongate member may be composed of multiplecomponents secured together in end-to-end relation. This modulararrangement of the elongate member may facilitate flexibility andcompatibility with multiple sizes of actuator and the like.

The inspection object may be engageable with one of the first and secondengagement members.

The inspection object may replicate or be in a similar form as anactuation object.

The inspection apparatus may be configured to be inserted into thehousing when said housing is connected to a further apparatus, such as adownhole tool.

The inspection apparatus may be arranged to be inserted into a downholeend of the actuator.

The inspection apparatus may be similar to an apparatus configured toinstall the indexing sleeve within the housing and positioned theindexing sleeve with the engagement members at a predetermined positionwithin the housing. In one embodiment the inspection apparatus maydefine or form part of an assembly apparatus, for use in assembling theindexing sleeve within the housing, and allowing a user to readilyidentify the position of the indexing sleeve relative to the housingduring assembly.

The downhole actuator may be provided separately from a downhole tool tobe actuated. In such an arrangement the downhole actuator may beconnected to or otherwise arranged adjacent to a downhole tool to permitthe actuator to actuate the downhole tool.

In some embodiments the downhole actuator may be deployable into awellbore independently of a downhole tool to be actuated. For example,the downhole actuator may be deployed and arranged adjacent to apreviously deployed downhole tool.

The downhole actuator may be deployable into a wellbore in combinationwith a downhole tool. For example, the downhole actuator and downholetool may form part of a common tool string.

The downhole actuator may be provided in combination with a downholetool, for example as part of a common downhole tool string or assembly.The downhole actuator may comprise a downhole tool.

In some embodiments the housing of the downhole actuator may define ahousing, or at least a portion of a housing of a downhole tool.

The downhole actuator may be for use in actuating a downhole valve. Thedownhole actuator may be for use in actuating a downhole fracturingvalve. The downhole actuator may be for use in actuating a flow by-passvalve. The downhole actuator may be for use in actuating an inflowcontrol valve.

The downhole actuator may be for use in actuating a downhole catchingarrangement. Such a catching arrangement may be for use in catching anobject, such as an object used to operate the downhole actuator.

The downhole actuator may be for use in actuating one or more slips,such as anchor slips. For example, the downhole actuator may directlyand mechanically manipulate or operate one or more slips. Alternatively,or additionally, the downhole actuator may function to provide a degreeof fluid communication control, for example to permit selectivehydraulic operation of one or more slips.

The downhole actuator may be for use in actuating one or more downholeseals, such as packers. For example, the downhole actuator may directlyand mechanically manipulate or operate a packer, for example byproviding a mechanical force, such as an axial force, compression forceor the like, to set, or unset, a packer. Alternatively, or additionally,the downhole actuator may function to provide a degree of fluidcommunication control, for example to permit selective hydraulicoperation of a packer, for example to establish fluid communicationbetween a packer assembly and a source of hydraulic power. For example,the downhole actuator may establish communication between a packerassembly and local hydrostatic pressure within a wellbore.

The downhole actuator may be for use in actuating one or more explosivecharges, such as might be used in a perforation gun.

The downhole actuator may be for use in actuating one or more downholeswitches, for example to reconfigure one or more downhole tools.

The downhole actuator may be for use in releasing on object, substance,chemical or the like from a downhole storage position. For example, thedownhole actuator may be for use in releasing an object, such as an RFIDtag or component, from a downhole location, to be subsequentlytransported within a wellbore system. The downhole actuator may be foruse in releasing a chemical, such as a tracer chemical or the like froma downhole location.

An aspect of the present invention relates to a downhole actuator,comprising:

a tubular housing; and

an indexing sleeve mounted within the housing and comprising an engagingarrangement which is engageable by an actuation object passing through acentral bore of the indexing sleeve to drive the indexing sleeve onediscrete step of movement through the housing towards an actuation site;

wherein the indexing sleeve is configured to be disabled when located ata disable region within the housing, such that the indexing sleeve, whendisabled, is not moved upon passage of an actuation object.

The indexing sleeve may be configured to be disabled at the actuationsite.

The indexing sleeve may be configured to function as a latch for adownhole tool when said indexing sleeve is disabled at the actuationsite.

The indexing sleeve may be configured to be disabled at a locationremote from the actuation site.

The tubular housing may define an indexing profile on an inner surfacethereof, wherein the engaging arrangement of the indexing sleevecooperates with said indexing profile to be engaged by an actuationobject.

The indexing profile may facilitate the indexing sleeve to becomedisabled.

The indexing profile may comprise a disabled region, wherein alignmentof the indexing sleeve with the disabled region of the indexing profilemay permit the indexing sleeve to become disabled.

The indexing profile may comprise a disabled region which coincides withthe actuation site of the actuator.

The indexing profile may comprise a disabled region which is remote fromthe actuation site.

The indexing sleeve may be configured to be moved towards the remotedisabled region by use of a shifting tool.

The indexing sleeve may define a shifting profile to facilitateengagement by a shifting tool.

An aspect of the present invention relates to an indexing sleeve. Suchan indexing sleeve may be as defined herein.

The indexing sleeve may be configured to be driven by one or moreactuation objects, such as balls, darts or the like. The indexing sleevemay be configured to be driven in a discrete movement step by anactuation object. The indexing sleeve may be configured to be driven ina number of discrete movement steps by a corresponding number ofactuation objects.

The indexing sleeve may be configured to cooperate with an indexingprofile on a separate object or structure. The indexing sleeve may beconfigured to cooperate with an indexing profile on a housing withinwhich the indexing sleeve is mounted.

The indexing sleeve may include an engaging arrangement to permitengagement with an actuation object. The engaging arrangement may permitengagement with an indexing profile. In one embodiment cooperation andengagement between the engaging arrangement, actuation object andindexing profile may permit the indexing sleeve to be driven by adiscrete movement step.

The engaging arrangement may include at least one engagement member. Theat least one engagement member may be radially movable. Such radialmovement may permit the at least one engagement member to be movedradially inwardly and outwardly to be selectively engaged by anactuation object and optionally an indexing profile. Such an actuationobject may pass through the indexing sleeve.

The engaging arrangement may comprise first and second engagementmembers. The first and second engagement members may be axially spacedfrom each other. The first and second engagement members may beconfigured to be sequentially engaged by an actuation object passingthrough the indexing sleeve to drive the indexing sleeve a discretemovement step.

The first and second engagement members may be arranged relative to eachother to permit only a single actuation object to be positionedtherebetween.

The indexing sleeve may be used in any suitable arrangement. Forexample, such an indexing sleeve may be used in an actuator, such as adownhole actuator. For example, the indexing sleeve may be moved in oneor more discrete movement steps towards an actuation site. Upon reachingan actuation site actuation of an associated tool may be initiated.

An aspect of the present invention relates to a downhole systemcomprising a downhole actuator and a downhole tool to be operated by thedownhole actuator. The downhole actuator may be as defined above.

The downhole system may comprise multiple downhole actuators, eachconfigured to operate one or more downhole tools.

An aspect of the present invention relates to a downhole tool. Thedownhole tool may comprise a tool housing defining a central bore andincluding a fluid port, such as a fluid port in a wall of the toolhousing. The fluid port may define a transverse fluid port. The fluidport may be configured to permit fluid communication between the centralbore and a location external to the housing. The fluid port may extendin any suitable direction. The fluid port may extend generallyperpendicularly relative to the central bore. In some embodiments thefluid port may extend generally obliquely relative to the central bore.The fluid port may extend in varying directions, for example portions ofthe fluid port may extend at least one of perpendicularly, parallel andobliquely relative to the central bore. The fluid port may be circular.The fluid port may be elongate, for example elongate in a longitudinaldirection of the housing.

A valve member may be mounted within the housing. The valve member maybe movable from a closed position in which the fluid port is blocked toan open position in which the fluid port is opened.

The valve member may comprise a valve sleeve. The valve member maycomprise a ball valve, flapper, gate or the like. The valve member maybe rotatably movable. The valve member may be linearly or axiallymovable.

The fluid port may be opened to provide fluid communication between thecentral bore of the tool and an external downhole location, such as anannulus, a surrounding formation or the like. The fluid port may bearranged to accommodate one or both of outflow and inflow.

A catching arrangement, such as a catching sleeve, may be mounted withinthe housing, for example on a downhole side of the valve sleeve. Thecatching arrangement may comprise one or more radially movable seatmembers. The catching arrangement may be configurable from a freeconfiguration in which the seat members permit an object to pass throughthe tool, to a catching configuration in which the seat members catch anobject passing through the tool.

The catching arrangement may be reconfigured by movement of the valvemember towards its open position. In such an arrangement movement of thevalve member towards its open position may function to initiate openingof the fluid port and also reconfigure the catching arrangement into itscatching configuration.

When the catching arrangement is configured in its catchingconfiguration an object passing through the downhole tool may seatagainst the seat members and become caught in the downhole tool. Wherethe catching arrangement is located downhole of the valve member, thecatching arrangement may function to catch an object on a downhole sideof the valve member and the fluid port.

When an object is caught by the catching arrangement, the object may atleast partially block flow through the central bore. This may functionto divert flow through the fluid port when opened.

When an object is caught by the catching arrangement the object mayfunction to cause movement, such as axial movement of the catchingarrangement. Such movement may function to provide further actuationwithin the downhole tool, such as further actuation of the valve member,to further reconfigure the catching arrangement, or the like.

In one embodiment the fluid port may be opened to permit a treatingfluid to be delivered from the central bore to an external location viathe fluid port. Such a treating fluid may be for use in treating asurrounding formation. The treating fluid may comprise a fracturingfluid for use in fracturing a surrounding formation, for examplehydraulically fracturing a formation. The treating fluid may comprise aproppant.

The treating fluid may comprise an acid, for example for acid matrixstimulation of a surrounding formation.

The downhole tool may define a fracturing tool.

A treating fluid may be for use in treating a wellbore, such as a wallsurface of a wellbore, wellbore infrastructure or the like.

The fluid port may be opened to permit a sealing fluid, such as cement,a swellable slurry or the like to be delivered from the central bore toan external location, for example for use in annulus isolation. Thefluid port may be opened to permit a loss-circulation material to becirculated outwardly from the tool.

The fluid port may be opened to permit inflow of a fluid into thecentral bore of the tool.

The downhole tool may be configured to permit an object to be caught inthe catching sleeve substantially simultaneously with or after the fluidport has been opened. In such an arrangement an object may be caught bythe catching arrangement after the fluid port has been opened. This maypermit a fluid flowing through the central bore of the tool housing tobe substantially arrested or restricted upon the object seating againstthe seat members and thus rapidly ejected through the fluid port. Suchrapid ejection may provide an impulse or fluid hammer effect which mayassist with initial penetration of the fluid into a surroundingformation. This may have particular application in fracturingoperations, in which initial rapid ejection of fluid from the fluid portmay assist with initial fracture of the surrounding formation.

In some embodiments this initial rapid ejection of fluid may permitmonitoring of the tool to be achieved. For example, a monitored pressurespike followed by a relatively quick reduction in pressure upstream ofthe downhole tool, such as upstream of the catching arrangement, mayprovide an indication that the fluid port has been successfully openedand an object has been caught in the catching arrangement.

The downhole tool may be configured to permit an object to be caught inthe catching arrangement prior to opening, or prior to complete opening,of the fluid port. In such an arrangement an object may be caught by thecatching arrangement before the fluid port has been opened or fullyopened. Once the object is caught, the fluid port may subsequently beopened or fully opened, for example by actuation by the catchingarrangement, by gradual increase of the fluid port area or the like.This arrangement may permit increased control over ejection of fluidthrough the fluid port. Further, this arrangement may avoid or minimizeany initial rapid ejection of fluid through the fluid port at the timethe object lands within the catching arrangement. That is, in thisarrangement fluid flowing through the tool may be substantially arrestedor restricted by the object when seated against the seat members of thecatching arrangement, with the fluid port closed or only partially open,thus minimizing any significant rapid ejection through the fluid port.The port may then be opened, allowing gradual initiation of fullejection rates through the port. This may be advantageous in certainapplications where an operator may wish to avoid rapid ejection, forexample to avoid damage to downhole systems or equipment or to thesurrounding formation.

In some embodiments rapid initial ejection may cause an initial periodof pressure fluctuations before a steady state condition is achieved.For example, rapid initial ejection may cause an initial pressure spike,followed by a subsequent pressure reduction below an intendedoperational pressure, prior to a more steady state pressure beingachieved. In some cases this dynamic pressure variation or profile mayprovide adverse effects, for example by causing premature release of acaught object or the like. For example, should release of an object fromthe catching arrangement be in response to a force or sequence of forceevents, then establishing initial pressure fluctuations within the toolmay inadvertently replicate such a force or sequence of force events,and prematurely release an object. As such, avoiding rapid fluidejection, for example as defined above, may be advantageous in thisregard also. For example, avoiding rapid initial ejection of fluidthrough the fluid port may permit the pressure within the tool to becontrolled in a more uniform or steady state manner, which may avoid anypressure fluctuations which could otherwise adversely affect anydownhole systems or operations.

The downhole tool may comprise a choke arrangement associated with thefluid port. Such a choke arrangement may function to choke flow throughthe fluid port once opened.

The downhole tool may comprise a variable choke arrangement associatedwith the fluid port. The variable choke arrangement may be configured toprovide a varying degree of choking to a flow through the fluid portonce opened. The variable choke arrangement may be configured to providea decreasing degree of choking to a flow through the fluid port onceopened. In such an arrangement, a maximum choking effect may be achievedupon opening of the fluid port, with the degree of choking decreasingover time. Such an arrangement may permit the pressure within the toolto be initially increased upon opening of the fluid port, but thengradually reduced following opening of the fluid port.

The variable choke arrangement may permit monitoring of the tool to beachieved. For example, upon opening of the fluid port the presence ofthe choke arrangement may provide a pressure increase followed by agradual reduction in pressure. This may allow an operator monitoring thepressure to identify correct operation of the tool, for example that thefluid port has opened sufficiently.

The variable choke arrangement may comprise a valve arrangement.

The variable choke arrangement may comprise the valve member. Forexample, the valve member may provide a variable opening of the fluidport to achieve variable flow choking.

The choke arrangement may comprise a choke member associated with, forexample mounted over or within, the fluid port. The choke arrangementmay define a variable orifice to provide variable choking to flowthrough the fluid port. The choke arrangement may define a variablyincreasing orifice to provide a variably decreasing choking effect.

The choke arrangement may comprise a dissipating member associated withthe fluid port. The dissipating member be arranged to dissipate inresponse to flow through the fluid port. The dissipating member maydefine an orifice, wherein said orifice is enlarged in response to flowthrough the fluid port. In such an arrangement, dissipation of thedissipating member may provide a reducing fluid choking effect.

The dissipating member may be dissipated by erosion, and as such thedissipating member may be erodible. Such an erodible dissipating membermay be of particular use in combination with a fracturing fluid whichincludes proppant.

The dissipating member may be dissipated by disintegration, for exampleby being broken up.

The choke arrangement may comprise a curved plate which is mounted onthe tool housing. The choke arrangement may be mounted on an outersurface of the housing. In embodiments where multiple fluid ports areprovided a single or a plurality of choke arrangements may be providedto operate in conjunction with the multiple fluid ports.

The valve member may be movable from its closed position towards itsopen position in response to an object passing through the downhole toolin a downhole direction. The same object which causes movement of thevalve member towards its open position may be caught by the catchingarrangement. Alternatively, a different object may be caught.

The valve member may be axially movable by an actuation member orarrangement mounted on an uphole side of the valve member. The actuationmember may move the valve member in a downhole direction.

The valve member may be axially movable by an indexing sleeve. Theindexing sleeve may be provided as described above. The indexing sleevemay be provided in accordance with a collet as disclosed in WO2011/117601 and/or WO 2011/117602. The disclosure provided in WO2011/117601 and WO 2011/117602 is incorporated herein by reference.

The indexing sleeve may form part of the downhole tool. The indexingsleeve may form part of a downhole actuator, which may be provided incombination with, or integrally with the downhole tool.

The indexing sleeve may be located on an uphole side of the valvemember. In such an arrangement the indexing sleeve may function to movethe valve member in a downhole direction. In one embodiment the indexingsleeve may be engageable, directly or indirectly, with the valve member.

The indexing sleeve may be operated to move linearly through the housingby passage of an object. In one embodiment the indexing sleeve may beoperated to move in a single discrete linear movement step to move thevalve member towards its open position.

In some embodiments the indexing sleeve may be operated to move in anumber of discrete linear movement steps by passage of a correspondingnumber of objects.

A plurality of discrete movement steps of the indexing sleeve mayfunction to move the valve member towards its open configuration. Insuch an arrangement a final discrete movement step of the indexingsleeve may function to move the valve member sufficiently to reconfigurethe catching arrangement to its catching configuration.

A final discrete movement step of the indexing sleeve may initiatemovement of the valve member towards its open position, and thus allowthe catching arrangement to become reconfigured during this finaldiscrete movement step. The indexing sleeve may be brought intoengagement with the valve member during a final discrete movement stepof the indexing sleeve.

Thus, following a final discrete step of linear movement of an indexingsleeve caused by a passing object, the valve member may be moved towardsits open position and the catching arrangement may be arranged in itscatching configuration. The catching arrangement may thus be arranged tocatch an object, such as the object which caused the final discretemovement step of the indexing sleeve.

In use, the indexing sleeve may be configured to temporarily capture apassing object to permit the object to drive the indexing sleeve adiscrete movement step, and subsequently release the object uponcompletion of the discrete movement step. During a final discretemovement step of the indexing sleeve by a temporarily captured object,the valve member may be moved sufficiently to reconfigure the catchingarrangement to its catching configuration, such that the object may becaught by the catching arrangement following release from the indexingsleeve.

The valve member and indexing sleeve may be arranged relative to eachother such that the valve member may be completely moved to its openposition during the final discrete movement step of the indexing sleeve.In such an arrangement the fluid port may be opened, for examplepartially or fully opened, during the final discrete movement step ofthe indexing sleeve.

The indexing sleeve may be configured to release an object substantiallysimultaneously with or subsequent to the valve member being positionedto open the fluid port and reconfigure the catching arrangement to itscatching configuration. In such an arrangement the released object maybe caught by the catching arrangement after the fluid port has beenopened. This may permit a fluid flowing through the central bore of thetool housing to be substantially arrested or restricted upon the objectseating against the seat members and thus rapidly ejected through thefluid port. Such rapid ejection may provide a fluid hammer effect.

Alternatively, the valve member and the indexing sleeve may be arrangedrelative to each other such that the valve member may be partially movedtowards its open position during the final discrete movement step of theindexing sleeve. In such an arrangement the fluid port may remainclosed, or be only partially open, following the final discrete movementstep of the indexing sleeve. In such an arrangement movement of thevalve member to its open configuration may be completed by analternative arrangement. For example, movement of the valve member maybe completed by the catching arrangement and a caught object. In oneembodiment an object seated against the seat members of the catchingarrangement may permit the catching arrangement to be moved axiallywithin the housing, for example by a fluid pressure differential acrossthe interface between the object and the seat members. Such axialmovement of the catching arrangement may cause further axial movement ofthe valve member to complete opening of the fluid port.

The indexing sleeve may be configured to release an object followingpositioning of the valve member to reconfigure the catching arrangementto its catching configuration with the fluid port still closed or onlypartially open. In such an arrangement the released object may be caughtby the catching arrangement before the fluid port has been opened orfully opened. Once the object is caught, the fluid port may subsequentlybe fully opened, for example by actuation by the catching arrangement.This arrangement may permit increased control over ejection of fluidthrough the fluid port. Further, this arrangement may avoid or minimizeany initial rapid ejection of fluid through the fluid port at the timethe object lands within the catching arrangement.

In one embodiment the valve member may reconfigure the catchingarrangement to its catching configuration upon the valve member reachingits open position. In such an arrangement the catching arrangement maybe permitted to catch an object after the fluid port in the tool housinghas been opened. This may permit a fluid flowing through the centralbore of the tool housing to be arrested or restricted within the centralbore of the tool upon an object seating against the seat members andthus rapidly ejected through the fluid port.

In one embodiment the valve member may reconfigure the catchingarrangement into its catching configuration prior to said valve memberreaching its open position. Such an arrangement may permit morecontrolled opening of the fluid port, which may minimize rapid initialejection of fluid. In one embodiment the valve member may be fullyactuated to open the fluid port by the catching arrangement. In such anarrangement the catching arrangement may be operated to move by thecaught object.

The valve member may be secured relative to the housing via a releasableconnection. Such a releasable connection may be provided to releasablysecure the valve member at its closed position. The releasableconnection may be releasable to permit movement of the valve membertowards its open position, for example axial movement of the valvemember towards its open position. The releasable connection may bereleasable upon application of a predetermined force, such as apredetermined axial force. The releasable connection may comprise ashear arrangement, such as one or more shear pins or the like.

The catching arrangement may be reconfigured to its catchingconfiguration by axial movement of the catching arrangement within thehousing.

The catching arrangement may be secured relative to the housing via areleasable connection. Such a releasable connection may be provided toreleasably secure the catching arrangement in its free configuration.The releasable connection may be releasable to permit axial movement ofthe catching arrangement to become reconfigured towards its catchingconfiguration. The releasable connection may be releasable uponapplication of a predetermined force, such as a predetermined axialforce. The releasable connection may comprise a shear arrangement, suchas one or more shear pins or the like.

The catching arrangement may be arranged to be axially moved by thevalve member.

The valve member may axially engage the catching arrangement to move thecatching arrangement. Such axial engagement may be achieved by abutmentof the valve member and catching arrangement in an axial direction. Suchabutment may be achieved by respective load profiles on the valve memberand catching arrangement. A load profile may comprise an end face, loadshoulder or the like.

The downhole tool may comprise a lost motion arrangement providedbetween the valve member and the catching arrangement. Such a lostmotion arrangement may permit the valve member to move a desireddistance relative to the catching arrangement before initiating axialmovement of the catching arrangement. The lost motion arrangement may bedefined by an initial axial separation of respective load profiles ofthe valve member and catching arrangement. The lost motion arrangementmay be adjustable.

The lost motion arrangement may permit an appropriate timing ofreconfiguring the catching arrangement to be achieved. For example, thelost motion arrangement may permit an appropriate timing ofreconfiguring the catching arrangement in accordance with opening of thefluid port. Such timing may be provided in accordance with release of anobject from an associated indexing sleeve or the like. Such timing ofevents may be as described above.

The valve member and catching arrangement may be axially engaged andconnected when one of the valve member and catching arrangement is movedin a direction towards the other. Such an arrangement may permit thevalve member to move the catching arrangement in the same direction oftravel as the valve member. The valve member and catching arrangementmay be axially disengaged when one of the valve member and catchingarrangement is moved in a direction away from the other. Such anarrangement may permit independent axial movement of the valve memberand catching arrangement when moved away from each other. Such anarrangement may facilitate independent actuation of the catchingarrangement, for example to be reconfigured towards a releaseconfiguration in which a caught object may be released.

The valve member and the catching arrangement may be rigidly securedtogether in an axial direction. In such an arrangement axial movement ofthe valve member in any direction may cause corresponding axial movementof the catching arrangement. Furthermore, such a rigid connection maypermit axial movement of the catching arrangement in any direction tocause corresponding axial movement of the valve member. Such anarrangement may be advantageous where the catching arrangement mustaxially move the valve member, for example to complete movement of thevalve member to its open position. A rigid connection between the valvemember and the catching arrangement may be releasable, for example inresponse to a predetermined force applied between said valve member andcatching arrangement. Such an arrangement may permit the valve memberand catching arrangement to become axially separated, at least in onerelative axial direction. Such axial separation may permit the catchingarrangement to be independently actuated relative to the valve member,if desired, for example to further reconfigure the catching arrangement,such as towards a release configuration, without disturbing the valvemember.

The valve member may comprise an axially extending shroud which extendsinto the catching arrangement from one axial end thereof. In such anarrangement the end region, which may be the uphole end region of thecatching arrangement may sit radially behind or on the outside of thevalve member shroud, and thus isolated from the central bore. Such anarrangement may function to protect the end of the catching arrangement,for example from engagement by an object travelling through the tool.Otherwise, an object passing through the tool may engage an exposed endface of the catching arrangement, which could provide adverse effects,such as damaging the catching arrangement, causing premature activationof the catching arrangement and the like.

The shroud may extend only partially through the catching arrangement.The shroud may terminate above the seat members to avoid interferencewith said seat members.

The shroud may extend into the catching arrangement at least when thecatching arrangement is configured in its free configuration.

The shroud may be generally cylindrical.

The shroud may comprise one or more ribs or fingers extending axiallyfrom the valve member.

The shroud may be integrally formed with the valve member.Alternatively, the shroud may be separately formed and subsequentlysecured or arranged with the valve member.

The shroud may define a proximal end which is engaged with the valvemember, for example integrally formed with the valve member. The shroudmay further define a distal or free end which is arranged to extend intothe catching arrangement.

The valve member may define a load shoulder in the region of theproximal end of the shroud for engaging a corresponding load face, suchas an axial end face, of the catching arrangement.

The valve member may define an annular notch formed in an outer surfaceand extending from one end thereof, such as a downhole end. An adjacentaxial end, such as an uphole end of the catching arrangement may bereceived within this annular notch. As such, the annular notch maydefine a shroud.

The annular notch may include a load shoulder, such as an annular loadshoulder for engaging the catching arrangement.

The annular notch may define a portion of a lost motion arrangement. Forexample, the catching arrangement may be initially positioned relativeto the valve member such that an axial separation exists between thecatching arrangement and a load shoulder of the annular notch, whereinthis separation is closed upon relative movement of the valve membertowards the catching arrangement.

The seat members may be radially movable to be radially extended andretracted relative to the central bore. That is, the seat members may bemovable radially inwardly to be retracted into the central bore todefine a reduced inner diameter. The seat members may be movableradially outwardly to be radially extended from the central bore todefine an increased inner diameter. When the seat members are positionedradially inwardly and retracted into the central bore said members maybe positioned into the path of an object passing through the tool. Whenin such a configuration the seat members may be engaged by an object.When the seat members are positioned radially outwardly and extendedfrom the central bore said members may be outside the path of an objecttravelling through the tool.

The seat members may be biased in a radial direction.

In one embodiment the seat members may be biased radially outwardly. Insuch an arrangement the seat members may require to be positively movedagainst this bias to be moved radially inwardly and be retracted intothe central bore to be engaged by an object. Thus, when the catchingarrangement is in its free configuration an object may freely passthrough the tool without or with minimal engagement with the seatmembers. The catching arrangement may be reconfigured into its catchingconfiguration by positively moving the seat members radially inwardlyinto the central bore against the bias to catch an object.

Biasing the seat members radially outwardly may minimize the exposure ofthe seat members to objects or fluid passing through the tool when thecatching arrangement is in its free configuration. This may minimizeenergy losses of a fluid and/or objects flowing through the tool. Also,this may minimize erosion or other damage to the seat members. Forexample, in some proposed uses of the tool a fluid carrying highlyabrasive particles, such as proppant, may flow through the tool, whichmay erode the seat members.

In one embodiment the seat members may be biased radially inwardly. Insuch an arrangement the seat members may require to be positively movedagainst this bias to be moved radially outwardly and be extended fromthe central bore to allow passage of an object, when required. Suchoutward radial movement of the seat members may be caused by an objectacting against the seat members during passage of the object through thetool when the catching arrangement is configured in its freeconfiguration.

The catching arrangement may be reconfigured to its catchingconfiguration by radially supporting the seat members in a radiallyinward position such that outward radial movement is prevented. In sucha configuration an object passing through the tool may become seatedagainst the radially supported seat members.

When the seat members are biased radially inwardly the catchingarrangement may be reconfigured to its catching configuration bysupporting the seat members in this biased radially inward position.

When the seat members are biased radially outwardly the catchingarrangement may be reconfigured to its catching configuration by bothpositively moving the seat members radially inwardly against the bias,and radially supporting the seat members to be retained in this inwardposition.

The downhole tool may define or comprise a first region within thehousing having a first inner diameter which permits the seat members tomove radially outwardly and be extended form the central bore whenaligned with said first region. In such an arrangement the catchingarrangement may be provided in its free configuration when the seatmembers are aligned with the first region.

The first region may comprise a recess or profile, such as an annularrecess or profile, configured to receive the seat members when said seatmembers are moved radially outwardly and extended form the central bore.The recess may define a profile which substantially corresponds to aprofile of the seat members. The recess may define a profile configuredto assist with transition of the seat members between radially extendedand retracted positions. For example, the recess may define a rampstructure configured to permit or assist with transition of the seatmembers, for example during relative axial movement between the seatmembers and the recess.

The downhole tool may define or comprise a second region within thehousing having a second inner diameter which permits the seat members tobe radially supported when positioned radially inwardly and retractedinto the central bore, when aligned with said second region. The secondregion may define a smaller inner diameter than the first region. Insuch an arrangement the catching arrangement may be provided in itscatching configuration when the seat members are aligned with the secondregion.

The first and second regions of the tool may be moved axially relativeto the catching arrangement to permit the catching arrangement to bereconfigured to its catching configuration.

The catching arrangement may be axially movable within the housing, forexample driven by the valve member, to realign the seat members from thefirst region to the second region, and thus present the catchingarrangement in its catching configuration.

The catching arrangement may be reconfigurable from the catchingconfiguration to a release configuration in which the seat memberspermit release of a previously caught object.

In one embodiment the catching arrangement may be reconfigurable to therelease configuration by de-supporting the seat members. When the seatmembers are de-supported a bias force may act to move the seat membersradially outwardly and extend the seat members from the central bore.Alternatively, or additionally, when the seat members are de-supporteddisplacement of an object, for example by fluid pressure, may deflectthe seat members radially outwardly, thus allowing the object to pass.

The catching arrangement may be axially movable within the housing, forexample in a downhole direction to permit said catching arrangement tobe reconfigured to the release configuration. Such axial movement may beachieved by action of an object seated against the seat members, forexample by action of a differential pressure permitted to be establishedacross the interface between the object and the seat members, by actionof kinetic energy or the momentum of an object or the like.

The catching arrangement may be axially movable to align the seatmembers with a region of increased inner diameter, thus permitting theseat members to be moved radially outwardly. The catching arrangementmay be axially movable to re-align the seat members with the firstregion of the housing. Alternatively, the catching arrangement may beaxially movable to be aligned with a third region within the housing,wherein said third region defines a greater inner diameter than thesecond region. Alternatively further, the second region within thehousing may be rearranged or modified to present an enlarged diameterwhich permits the seat members to be moved radially outwardly.

The downhole tool may comprise a release arrangement. Such a releasearrangement may be actuated by axial movement of the catchingarrangement, for example in a downhole direction. The releasearrangement may be configured to facilitate de-supporting of the seatmembers to permit the catching arrangement to be configured in itsrelease configuration.

The downhole tool may comprise a release member, such as a sleeve,mounted within the housing. The release member may be movable between asupporting position in which the release member may radially support theseat members in the radially inward or retracted position, towards ade-supporting position in which the release member removes the radialsupport to the seat members, allowing the seat members to be movedradially outwardly.

The release member may be located in its supporting position at thesecond region within the housing. Accordingly, the release member maydefine the second inner diameter.

The downhole tool may comprise or define a release recess within thehousing. The release member may cover this release recess when saidrelease member is located within its supporting position. The releasemember may be moved axially within the housing towards its releaseposition to uncover the release recess and thus permit the seat membersto be moved radially outwardly and received within the release recess topermit release of an object.

The release member may be moved axially by an actuator.

The release member may be moved axially by the catching arrangement.

The release member may define a load profile, such as a load shoulder,configured to be engaged by the catching arrangement.

The catching arrangement may define a load profile configured to engagea load profile on the release member to permit the catching arrangementto apply a force on the release member.

One or more seat members may comprise a load profile, such as a notch,configured to engage a load profile on the release member to permit therelease member to be moved by the catching arrangement. One or more seatmembers may comprise a load profile on a radially outer surface thereofand configured to engage a corresponding load profile, such as anannular shoulder, on a radially inner surface of the release member.

Each seat member may comprise a load profile, wherein when said seatmembers are moved radially inwardly the individual load profiles definea substantially circumferentially continuous load profile.

The catching arrangement may be biased in a preferred axial direction.In one embodiment the catching arrangement may be biased in a directionopposite to the direction in which the release member is moved to bepositioned within its release position. Such an arrangement may permitthe catching arrangement to be axially returned, following actuation ofthe release member, to a position at which the seat members are alignedwith an/the uncovered release recess.

The catching arrangement may be associated with a bias arrangement. Thebias arrangement may act between the catching arrangement and thehousing. In some embodiments, the catching arrangement may be rotatablysecured relative to the housing by a bias arrangement. Such anarrangement may permit the catching arrangement to be machined when insitu, for example by a milling operation. In one embodiment one end of abias arrangement may be rotatably secured to the catching arrangement,and an opposite end of the bias arrangement may be rotatably secured tothe housing

The catching arrangement may define a bias profile, such as a shoulder,configured to be engaged by a bias arrangement. The bias profile mayinclude a connection profile to permit rotatable connection between thecatching arrangement and the bias arrangement. Such a connection profilemay include an axially extending slot or the like, wherein said slot mayreceive an axially extending portion of the bias arrangement.

The catching arrangement may be biased by a spring arrangement, such asa coiled spring member or the like.

The seat members may collectively define a substantially completeannular structure when positioned radially inwardly and retracted intothe central bore (for example when the catching arrangement isconfigured in its catching configuration). In such an arrangement eachseat member may be engaged or be brought into very close proximity withtwo circumferentially adjacent seat members when positioned radiallyinwardly.

The ability to provide a substantially complete annular structure maypermit a high degree of sealing to be achieved between the seat membersand an object when seated against the seat members. Such sealing maypermit a pressure to be elevated on the object side of the seat members,for example to facilitate certain downhole operations. Such sealing maypermit a pressure differential to be established axially across theobject. Such sealing may permit the object, when seated against the seatmembers, to function as an efficient flow diverter, preventing orsubstantially minimizing flow by-passing the object.

Adjacent seat members may be configured to define a gap therebetweenwhen the seat members are positioned radially inwardly (for example whenthe catching arrangement is configured in its catching configuration).The width of the gap between adjacent set members may be provided belowa preferred maximum gap width. Such a preferred maximum gap width may beselected in accordance with a fluid being communicated through the tool.In one embodiment a preferred maximum gap width may be defined orselected in accordance with the dimension of a particle or particles,such as proppant, being carried by a fluid communicated through thetool. In such an arrangement the maximum gap width may be selected inaccordance with the ability of individual particles to bridge the gapbetween adjacent seat members to facilitate improved sealing.

In one embodiment a preferred maximum gap width between adjacent sealmembers when positioned radially inwardly (for example when the catchingsleeve is configured in its catching configuration) may be defined inaccordance with a mean dimension of particles, such as proppant, beingcarried by a fluid communicated through the tool. A maximum preferredmaximum gap width may be selected to be in the region of 1 to 20 timesthe mean particle diameter, for example in the region of 1 to 10 timethe mean particle diameter, such as between 1 to 5 times the meanparticle diameter. In one embodiment a preferred maximum gap width maybe in the region or twice the mean particle diameter.

In some embodiments the seat members may be arranged to permit a degreeof fluid bypass when an object is seated against said seat members. Suchfluid bypass may be provided to establish a desired back pressure withinthe tool. Such fluid by-pass may provide a degree of contingency, forexample in the event of an object failing to be released.

The ability to provide a substantially complete annular structure maypermit a more robust structure to be formed, which may facilitateimproved mechanical response to the operational forces, such as impactforces upon engagement by an object, actuation forces by an objectseated against the seat members and the like.

One or more seat members may define a seat surface on one axial sidethereof. Such a seat surface may be configured to be engaged by anobject.

The seat surface of a seat member may be arranged to provide asubstantially continuous or complete engagement with an object. Such anarrangement may permit sealing engagement to be achieved between theseat surface and an object. In one embodiment the seat surface maydefine a circumferential profile which corresponds to a circumferentialprofile of an object.

The seat surface of a seat member may be arranged to providediscontinuous or incomplete engagement with an object. Such anarrangement may permit non-sealing engagement to be achieved between theseat surface and an object, for example to permit flow by-pass. In oneembodiment a seat surface may comprise or define an axially extendingslot or channel. Such a slot or channel may facilitate fluidcommunication axially along the seat surface even with an object engagedagainst said surface.

One or more seat members may define a curved seat surface. One or moreseat members may define a convex seat surface. Such an arrangement maybe provided in combination with use of an object having a curved, suchas convex surface.

Providing a curved seat surface, and in particular a convex seatsurface, may assist to prevent or at least mitigate the swaging, jammingor otherwise lodging of an object relative to the seat members. This maypermit the object to be subsequently readily removed, if desired.

Providing a curved seat surface, and in particular a convex seat surfacemay permit a greater degree of control over the transmission of loadforces between an object and the associated seat member, when engaged,and to other components of, or operatively associated with, the catchingarrangement. For example, in embodiments of the invention the engagementbetween the seat members and an object may be configured so that theload path of a resultant force transmitted to the seat members may becontrolled or selected to maximize the transmission of load forces alonga particular vector in order to activate another component of, oroperatively associated with, the downhole tool and/or to eliminate ormitigate moment forces.

A curved seat surface, and in particular a convex seat surface mayfunction to minimize the contact area between the seat and the object;in contrast to conventional arrangements which seek to maximize thecontact area between a seat and the object.

The seat surface of a seat member may be configured to provide a line orpoint engagement between the associated seat member and an object.

The seat surface of a seat member may comprise a hemi-toroidal surface,d-shaped in longitudinal section or the like.

The seat surface of a seat member may comprise a linear convex surface.For example, the seat surface may comprise a toroidal polyhedronsurface, triangular in longitudinal section or the like.

One or more seat members may be configured to be engaged by an objectfrom opposing axial directions. Such an arrangement may permit an objectto be caught or arrested when passing in either axial direction. Forexample, in some embodiments reverse flow through the tool may cause anobject which has previously passed in a forward direction to be engagedor seated against the seat members. Further, such an arrangement maypermit the catching arrangement to be actuated to move in opposing axialdirections in response to engagement by an object passing through thetool in either axial direction. Such an arrangement may facilitateremedial action, for example in the event of the catching arrangementbecoming jammed or the like, wherein release of the catching arrangementmay be achieved by reverse flow of an object from below or downhole ofthe tool. Such an arrangement may permit a degree or re-setting of thetool to be achieved, for example to return the valve member to a closedor partially closed position, to return the catching arrangement to itsfree configuration or the like.

One or more seat members may comprise a first seat surface on one axialside thereof, and a second seat surface on an opposing axial sidethereof.

The seat surfaces may be defined as above.

In one embodiment both the first and second seat surfaces may beconfigured similarly. For example both the first and second seatsurfaces may be configured to permit sealing engagement to be achievedwhen engaged by an object from either axial side of the catchingarrangement. Further, both the first and second seat surfaces may beconfigured to permit non-sealing engagement to be achieved when engagedby an object.

In one embodiment, one of the first and second seat surfaces may permitsealing engagement to be achieved, and the other of the first and secondseat surfaces may be configured to permit non-sealing engagement to beachieved. In one embodiment a seat surface on an uphole side of a seatmember may be configured to permit sealing engagement, and a seatsurface on a downhole side of the seat member may be configured topermit non-sealing engagement.

The catching arrangement may comprise or define a collet sleeve. Thecollet sleeve may comprise a tubular portion and a plurality of colletfingers supported by the tubular portion. The tubular portion and thecollet fingers may be integrally formed.

Each collet finger may support a respective seat member. Each colletfinger may be integrally formed with a respective seat member. A distalend of each collet finger may support a respective seat member. Eachcollet finger may be radially deformable to permit the respective seatmembers to be moved radially outwardly and inwardly. The collet fingersmay be elastically deformable to provide a desired radial bias.

At least one and in some embodiments all collet fingers may define atapering radial width. Such a tapering radial width may assist tocontrol stress and/or strain within a collet finger. For example, such atapering radial width may assist to provide uniform stress distributionwithin a collet finger during deformation thereof. Further, such atapering radial width may permit a collet finger to bend more uniformlyalong its length, rather than focusing deformation at a discretelocation.

In some embodiments the radial width may taper from one end of a colletfinger to an opposite end. The radial width may taper such that a regionof a collet finger adjacent the tubular portion defines a greater radialwidth than a region adjacent an associated seat member.

The radial width of a collet finger may taper in a linear manner. Theradial width of a collet finger may taper in a non-liner, such as acurved, manner.

The collet fingers may extend in a downhole direction from the tubularportion. The tubular portion may be provided on an uphole side of thecollet sleeve.

The tubular portion may be positioned adjacent the valve member. Thetubular portion may be configured to be engaged by the valve member, forexample to permit the valve member to axially move the catchingarrangement. A shroud portion of the valve member may be arranged to bereceived within the tubular portion.

The collet sleeve may be formed as a unitary component.

In one embodiment the collet sleeve may be manufactured or formed as asingle collet component with the seat members initially provided as aunitary annular structure. Such a unitary collet component may beinitially formed by casting, machining or the like. In one embodimentthe collet may be initially formed from a raw stock material, such as acylindrical billet, bloom or the like. The unitary annular structure maybe formed with a geometry which represents a radially inwardly retractedposition of the seat members.

The unitary collet component may be initially formed with the tubularportion, the single unitary annular structure, and a plurality of ribstructures extending between the tubular portion and the unitary annularstructure. The rib structures may be generally tapered, for exampleconical. For example, the tubular portion may define a larger diameter,such as outer diameter, than the unitary annular structure, such thatthe ribs may be generally tapered. In some embodiments the ribstructures may be provided as a unitary sleeve or conical shapestructure.

The rib structures may define a tapering width.

The unitary annular structure may be subsequently divided to provide theindividual seat members. Such division may be achieved by, for example,EDM machining, wire cutting, laser cutting, waterjet cutting, or anyother suitable cutting or dividing process. Such cutting or division mayinvolve minimal material removal such that the individual seat membersmay be presented in very close proximity when positioned within theirradially inwardly retracted position. This arrangement of initiallyforming the seat members as a single component may assist to providevery accurate tolerances and include very detailed and accurate featureswithin the catching arrangement/collet sleeve. Further, such amanufacturing arrangement or method may permit very close control overthe form of the collective structure formed by the individual seatmembers when located within their radially inwardly retracted position.

Division of the unitary annular structure may also define the individualcollet fingers. For example, following division of the unitary annularstructure each rib structure may define a collet finger. Alternatively,individual collet fingers may be defined by division of a largerstructure, such as a further sleeve or conical shaped structure.

Following division of the unitary annular structure the seat members maybe retained in their initially divided configuration, that is, in closeproximity to each other and defining their radially inwardly retractedposition. In such an arrangement the seat members may be biased towardstheir radially inwardly retracted position.

In an alternative embodiment, following division of the unitary annularstructure, the collet fingers may be plastically deformed radiallyoutwardly. Such plastic deformation may be achieved by driving the seatmembers and associated fingers over a cone or mandrel. In such anarrangement the seat members may be initially provided in their radiallyoutwardly extended position. As such, the seat members may be biasedtowards this radially outwardly extended position.

Aspects of the present invention relate to a method for manufacturing acollet sleeve, such as a catching arrangement, for example as describedabove.

The method may comprise forming a unitary component, for example from asingle raw stock material, which includes a tubular portion and a singleunitary annular structure which are axially interconnected via aconnecting structure. The connecting structure may be tapered, forexample conical.

The connecting structure may comprise a plurality of ribs. The ribs maydefine a tapering width.

The method may comprise dividing the unitary annular structure, forexample by EDM machining, wire cutting, laser cutting, waterjet cutting,or any other suitable cutting or dividing process.

Such division of the single unitary annular structure may defineindividual collet fingers having a collet member, such as a seat memberintegrally formed at a distal or free end.

The method may comprise deforming the individual collet fingers radiallyoutwardly.

The tool housing may comprise a plurality of fluid ports. Such fluidports may be circumferentially distributed around the housing.

In some embodiments a plurality of fluid ports may be circumferentiallydistributed around the housing at an equal spacing.

The housing may define a plurality of port regions around itscircumference. The port regions may be evenly distributed around thehousing. Each port region may comprise a fluid port. At least one portregion may be absent from a fluid port. In such an arrangement a portregion without any port may provide a region for permitting otherinfrastructure, such as conduits or the like, to run along the housing,without interfering with a port. Such an arrangement may assist tominimize damage to any infrastructure running along the housing by fluidexiting the fluid ports.

The flow area of the fluid port or ports may be provided in a desiredratio relative to the central bore. In some embodiments the flow area ofthe fluid port or ports may be less than the flow area of the centralbore.

In some embodiments the flow area of the fluid port or ports may besubstantially equal to the flow area of the central bore.

In some embodiments the flow area of the fluid port or ports may begreater than the flow area of the central bore. Such an arrangement mayfacilitate efficient outflow of fluid from the central bore. Further,such an arrangement may facilitate a flow bias in an outflow direction.

The flow area of the fluid port or ports may be in the region of 1.05 to1.5 times greater than the flow area of the central bore, for example inthe range of 1.05 to 1.3 times greater. In one embodiment the flow areaof the fluid port or ports may be in the region of 1.1 times greaterthan the flow area of the central bore.

The valve member may comprise a port or aperture in a side wall thereof.Alignment of the port of the valve member with the fluid port may permitthe fluid port to be opened. Where the tool housing includes multiplefluid ports the valve member may include a corresponding number of portsor apertures. The port or aperture in the valve member may be circular.Alternatively, the port or aperture may be elongate. The port oraperture may be elongate in a direction in which the valve member isarranged to move to align said port or aperture with the fluid port inthe housing. The port or aperture may be elongate in an axial directionrelative to the valve member. Providing an elongate port or aperture mayfacilitate improved alignment between the port of the valve sleeve andthe fluid port in the housing.

The valve member may be rotatably secured relative to the housing via arotary coupling. The rotary coupling may prevent the valve member fromrotating relative to the housing. The rotary coupling may permitrelative axial movement of the valve member relative to the housing. Therotary coupling may comprise a spline arrangement. The rotary couplingmay comprise a key and key-way arrangement. The rotary coupling may alsofunction to rotatably secure other components relative to the housing,such as the catching arrangement. The rotary coupling may permit axialmovement between components of the tool, such as the valve member,catching arrangement, housing or the like.

The rotary coupling may permit appropriate alignment of the fluid portwith a port or aperture provided in the valve member.

The rotary coupling may facilitate milling or other rotary machiningoperation of the valve member in situ. Such an arrangement may permitthe valve member to be milled through during a remedial operation or thelike.

The tool may comprise one or more sealing arrangements provided on anouter surface thereof, for example on an outer surface of the housing.The seals may be configured to isolate a downhole region, for example anannular region, surrounding the tool. Such an arrangement may assist tofacilitate focusing of any outflowing fluid from the tool to a preciselocation. In fracturing operations, such a sealing arrangement mayassist to permit improved geological penetration of a fracturing fluid.

The tool may comprise a sealing arrangement on one, or alternatively onopposing axial sides of the fluid port. The sealing arrangement may beconfigured to provide sealing within an annulus which surrounds thetool. The sealing arrangement may be configured to provide completesealing. The sealing arrangement may be configured to provide a flowrestriction within the annulus. This may provide or permit an isolatedor flow restricted region to be formed in the region of the fluid port.

One or more sealing arrangements may comprise a packer.

One or more sealing arrangements may be actuated by an actuator, or aplurality of actuators.

In some embodiments a plurality of sealing arrangements may be provided.In such an arrangement at least two sealing arrangements may beconfigured to be actuated independently of each other or dependently ofeach other. The sealing arrangements may be actuated in any desiredsequence.

One or more sealing arrangements may be activated by outflow from thetool. One or more sealing arrangements may comprise or define a cup sealarrangement.

One or more sealing arrangements may comprise a flow restrictor.

One or more sealing arrangements may be provided in accordance with theflow restrictor disclosed in PCT application no. PCT/GB2012/051788, thedisclosure of which is incorporated herein by reference.

The flow restrictor may be configured so as to permit the flowrestrictor to slip over another body, for example but not exclusivelythe housing of the tool, associated connectors or the like. Permittingthe flow restrictor to slip over the tool may allow the flow restrictorto be positioned in close proximity to the fluid port, which may provideadvantages in terms of focusing flow from the fluid port at a desiredregion.

The flow restrictor may be of any suitable form or construction.

The flow restrictor may comprise a flow actuable flow restrictor.

The flow restrictor may be actuable by fluid flow over the flowrestrictor. The flow restrictor may be actuable by fluid flow from thefluid port. Such an arrangement may eliminate or minimize therequirement to provide further dedicated actuation of the flowrestrictor.

The flow restrictor may be actuable by fluid flow above a threshold flowrate.

The flow restrictor may be configured to hold a pressure differentialwithin the annulus. The flow restrictor may be configured to hold apressure of at least 3000 psi (20.7 MPa) in the annulus. The flowrestrictor may be configured to hold a pressure of at least 5000 psi(34.5 MPa) in the annulus. The flow restrictor may be configured to holda pressure of at least 7500 psi (51.7 MPa) in the annulus.

At least part of the flow restrictor may be configured to deform abovethe threshold flow rate to move the flow restrictor from a run-inconfiguration to a set configuration.

The flow restrictor may comprise a flow restrictor body. The flowrestrictor body may be configured so as to permit the flow restrictor toslip over the tool, associated connector or the like. Alternatively, theflow restrictor may be provided on a sub configured for coupling to thetool.

The flow restrictor may comprise a restrictor assembly. The restrictorassembly may be mounted on the flow restrictor body.

The restrictor assembly may be actuable between a run-in configurationand a set configuration.

In the set configuration, at least a portion of the restrictor assemblymay be radially splayed to substantially restrict flow in the annulus.

The flow restrictor may be actuable by fluid flow over the restrictorassembly.

At least part of the restrictor assembly may be configured to deformabove the threshold flow rate to move the flow restrictor from therun-in configuration to the set configuration.

At least part of the flow restrictor may be configured to plasticallydeform such that the flow restrictor remains in the set configurationfollowing actuation.

The value of the threshold flow rate may be selected to exceed the flowrates to which the flow restrictor is exposed while the tool is run-into a bore.

The threshold flow rate over the restrictor assembly may be above 5barrels per minute.

The flow restrictor can have a central axis and at least a part of therestrictor assembly may be inclined at an angle relative to the centralaxis.

The angle of incline of the flow restrictor relative to the central axismay be shallow to reduce the likelihood of premature setting of the flowrestrictor.

The angle of incline of the restrictor assembly may be between one andfifteen degrees relative to the central axis.

The angle of incline may be between one and seven degrees relative tothe central axis. The angle of incline may be around 3.5 degreesrelative to the central axis.

The body may be tapered to define the angle of incline of the restrictorassembly mounted on the body. The body may be a mandrel or a tool shaft.

An aspect of the present invention relates to a downhole catchingarrangement for catching an object. The object may comprise an actuationobject. The object may comprise a ball, dart, or the like.

The catching arrangement may be configured to catch an object travellingdownhole, for example travelling through a tubular structure positionedwithin a wellbore, such as a tubing string, tool string or the like. Thecatching arrangement may be configured to be located within a tubularstructure. For example, the catching arrangement may be configured to bemounted within a housing of a downhole tool.

The catching arrangement may define or comprise a catching sleeve.

The catching arrangement may be as defined herein, for example asdefined above.

The catching arrangement may be configured to function as a flowdiverter when an object is caught.

The catching arrangement may be configured to function as an actuatorwhen an object is caught. For example, the catching arrangement may beconfigured to actuate another component, structure, apparatus, tool orthe like. For example, when an object is caught by the catchingarrangement, the object may facilitate movement of the catchingarrangement, for example by impact of the object against the catchingarrangement, by a pressure differential established across theobject/catching arrangement, or the like.

The catching arrangement may be configured to function as a bore plugwhen an object is caught, for example to isolate a region within atubing structure. Such an arrangement may facilitate pressure to becontrolled, for example elevated, in a section of a tubular structure.Such an arrangement may facilitate pressure actuation of a furthercomponent, structure, apparatus, tool or the like, such as packers,slips, rupture disks and the like.

The catching arrangement may be configured to function as a flowrestrictor when an object is caught. For example, the catchingarrangement may be configured to function as a choke.

The catching arrangement may include a plurality of radially movableseat members configured to be engaged by an object.

The catching arrangement may be configurable between a freeconfiguration in which the seat members permit an object to pass thecatching arrangement, to a catching configuration in which the seatmembers catch an object.

The catching arrangement may be reconfigured between its free andcatching configurations by an actuator. Any suitable actuator may beused to actuate and reconfigure the catching arrangement. For example, avalve member, such as a valve sleeve, arranged in proximity to thecatching sleeve may function to reconfigure the catching arrangement.For example, opening and/or closing of a valve member may alsoreconfigure the catching arrangement.

An indexing sleeve, such as defined herein, may be used to reconfigurethe catching arrangement. A collet as disclosed in WO 2011/117601 and/orWO 2011/117602 may be used to reconfigure the catching arrangement.

A piston assembly may be used to reconfigure the catching arrangement. Ashifting tool, such as a coiled tubing or wireline deployed shiftingtool may be used to reconfigure the catching arrangement.

The seat members may be radially movable to be radially extended andretracted relative to a central bore of the catching arrangement. Thatis, the seat members may be movable radially inwardly to be retractedinto the central bore to define a reduced inner diameter. The seatmembers may be movable radially outwardly to be radially extended fromthe central bore to define an increased inner diameter. When the seatmembers are positioned radially inwardly and retracted into the centralbore said members may be positioned into the path of an object passingthrough the catching arrangement. When in such a configuration the seatmembers may be engaged by an object. When the seat members arepositioned radially outwardly and extended from the central bore saidmembers may be outside the path of an object travelling through thecatching arrangement.

The seat members may be biased in a radial direction.

In one embodiment the seat members may be biased radially outwardly. Insuch an arrangement the seat members may require to be positively movedagainst this bias to be moved radially inwardly and be retracted intothe central bore to be engaged by an object. Thus, when the catchingarrangement is in its free configuration an object may freely passthrough the catching arrangement without or with minimal engagement withthe seat members. The catching arrangement may be reconfigured into itscatching configuration by positively moving the seat members radiallyinwardly into the central bore against the bias to catch an object.

In one embodiment the seat members may be biased radially inwardly. Insuch an arrangement the seat members may require to be positively movedagainst this bias to be moved radially outwardly and be extended fromthe central bore to allow passage of an object, when required. Suchoutward radial movement of the seat members may be caused by an objectacting against the seat members during passage of the object through thecatching arrangement when the catching arrangement is configured in itsfree position.

The catching arrangement may be reconfigured to its catchingconfiguration by radially supporting the seat members in a radiallyinward position such that outward radial movement is prevented. In sucha configuration an object passing through the catching arrangement maybecome seated against the radially supported seat members.

The catching arrangement may be axially movable to be configured betweenits free and catching configurations.

The catching arrangement may be configured to release a previouslycaught object. The catching arrangement may be configured to release apreviously caught object by establishing a condition, such as a pressurecondition, flow condition or the like within the downhole tool. Thecatching arrangement may be configured to release a previously caughtobject by a change in flow direction, for example reverse flow throughthe downhole tool.

The catching arrangement may be reconfigurable from the catchingconfiguration to a release configuration in which the seat memberspermit release of a previously caught object.

The catching arrangement may be reconfigured to an intermediate releaseconfiguration, for example by action of a caught object acting againstthe catching arrangement. The catching arrangement may be reconfiguredfrom an intermediate release position to a release configuration by avariation I a downhole condition, for example a variation in pressure,flow rate, flow direction or the like.

When the catching arrangement is configured in a release configuration,the catching arrangement may permit an object to pass. In such anarrangement the release configuration of the catching arrangement mayalso define a free configuration.

In one embodiment the catching arrangement may be reconfigurable to therelease configuration by de-supporting the seat members. When the seatmembers are de-supported a bias force may act to move the seat membersradially outwardly and extend the seat members from the central bore.Alternatively, or additionally, when the seat members are de-supporteddisplacement of an object, for example by fluid pressure, may deflectthe seat members radially outwardly, thus allowing the object to pass.

The catching arrangement may be axially movable to permit said catchingarrangement to be reconfigured to the release configuration. Such axialmovement may be achieved by action of an object seated against the seatmembers, for example by action of a differential pressure permitted tobe established across the interface between the object and the seatmembers.

The catching arrangement may be axially movable to align the seatmembers with a region of increased inner diameter, thus permitting theseat members to be moved radially outwardly. 103931 The catchingarrangement may be provided in combination with a release arrangement.The catching arrangement and the release arrangement may form part of acatching system according to an aspect of the present invention. Therelease arrangement may be actuated by axial movement of the catchingarrangement, for example in a downhole direction. The releasearrangement may be configured to facilitate de-supporting of the seatmembers to permit the catching arrangement to be configured in itsrelease configuration.

The release arrangement may comprise a release member, such as a releasesleeve. The release member may be movable between a supporting positionin which the release member may radially support the seat members in theradially inward or retracted position, towards a de-supporting positionin which the release member may remove the radial support to the seatmembers, allowing the seat members to be moved radially outwardly.

The release member may cover a release recess, for example formed withina tubing structure, when said release member is located within itssupporting position. The release member may be moved axially towards itsrelease position to uncover the release recess and permit the seatmembers to be moved radially outwardly and received within the releaserecess to permit release of an object.

The release member may be moved axially by an actuator.

The release member may be moved axially by the catching arrangement.

The release member may define a load profile, such as a load shoulder,configured to be engaged by the catching arrangement.

The catching arrangement may define a load profile configured to engagea load profile on the release member to permit the catching arrangementto apply a force on the release member.

One or more seat members may comprise a load profile, such as a notch,configured to engage a load profile on the release member to permit therelease member to be moved by the catching arrangement. One or more seatmembers may comprise a load profile on a radially outer surface thereofand configured to engage a corresponding load profile, such as anannular shoulder, on a radially inner surface thereof.

Each seat member may comprise a load profile, wherein when said seatmembers are moved radially inwardly the individual load profiles definea substantially circumferentially continuous load profile.

The catching arrangement may be biased in a preferred axial direction.In one embodiment the catching arrangement may be biased in a directionopposite to the direction in which the release member is moved to bepositioned within its release position. Such an arrangement may permitthe catching arrangement to be axially returned, following actuation ofthe release member, to a position at which the seat members may bealigned with an/the uncovered release recess.

An aspect of the present invention relates to a downhole actuator foractuating a downhole tool, comprising:

a tubular housing including an indexing profile on an inner surfacethereof; and

an indexing arrangement mounted within the housing and arranged toprogress linearly through the housing towards an actuation site in apredetermined number of discrete steps of linear movement by passage ofa corresponding number of actuation objects through a central bore ofthe indexing arrangement,

wherein the indexing arrangement comprises an engaging arrangementincluding first and second engagement members which cooperate with theindexing profile of the housing to be selectively engaged by anactuation object passing through the central bore of the indexingarrangement to drive the indexing arrangement one discrete step, whereinthe engagement members are arranged relative to each other to permitonly a single actuation object to be positioned therebetween.

An aspect of the present invention relates to a method for downholeactuation using any downhole actuator and/or tool as described herein.

An aspect of the present relates to a method for downhole actuation,comprising:

providing an indexing arrangement defining a central bore and includingan engaging arrangement including first and second engagement members;

locating the indexing arrangement within a housing defining an indexingprofile configured to cooperate with the first and second engagementmembers of the indexing arrangement to cause said engagement members tobe selectively moved radially relative to the central bore of theindexing arrangement;

locating the indexing arrangement and housing in a wellbore; and

delivering an object through the indexing arrangement to selectivelyengage at least one of the first and second engagement members to drivethe indexing arrangement at least one discrete movement step towards anactuation site.

An aspect of the present invention relates to a downhole actuationsystem comprising a plurality of downhole actuators such as describedherein. At least two downhole actuators may be configured to permitactuation of respective associated downhole tools upon passage of adifferent number of actuation objects.

At least two downhole actuators may be configured to permit actuation ofsimilar downhole tools.

At least two downhole actuators may be configured to permit actuation ofdifferent downhole tools.

The plurality of downhole actuators may be arranged to permit operationof their associated downhole tools in any desired sequence.

An aspect of the present invention relates to a downhole tool,comprising:

a tool housing defining a central bore and including a fluid port;

a valve member mounted within the housing and being movable from aclosed position in which the fluid port is blocked to an open positionin which the fluid port is opened; and

a catching arrangement mounted within the housing on a downhole side ofthe valve member and including a plurality of radially movable seatmembers,

wherein movement of the valve member towards its open positionreconfigures the catching arrangement from a free configuration in whichthe seat members permit an object to pass through the tool, to acatching configuration in which the seat members catch an object passingthrough the tool.

An aspect of the present invention relates to a downhole tool,comprising:

a tool housing defining a central bore and including a fluid port; and

a catching arrangement mounted within the housing and including aplurality of radially movable seat members,

wherein the catching arrangement is configurable between a freeconfiguration in which the seat members permit an object to pass throughthe tool, to a catching configuration in which the seat members catch anobject passing through the tool to divert flow through the fluid port.

An aspect of the present invention relates to a method for treating asubterranean region, such as a formation. Treating may comprisefracturing, acid stimulation or the like. The method for treating maycomprise use of any downhole actuator and/or tool as described herein.

An aspect of the present invention relates to a mechanical countingdevice locatable at each of a plurality of downhole tools arrangedwithin and along a well bore, each tool having a main bore correspondingto the well bore, and each tool being actuatable to open one or morefluid ports which are transverse to the main bore, the mechanicalcounting device comprising:

a linear indexing arrangement adapted to cause the mechanical countingdevice to linearly progress along the main bore by a predetermineddistance in response to receiving an object dropped down the well boreuntil reaching an actuation site of the tool whereupon the tool isactuated,

wherein the linear indexing arrangement is configured to only allowprogress along the main bore by the predetermined distance in responseto receiving a single object dropped down the well bore.

An aspect of the present invention relates to a valve actuator for adownhole tool having a main bore corresponding to the well bore, thetool being actuatable to open one or more fluid ports which aretransverse to the main bore, the actuator comprising:

a catching device mountable within the main bore and having a firstconfiguration in which the device allows the passage of an objectdropped down the well bore and a second configuration in which thedevice catches the dropped object;

a switching arrangement which is operable to switch the catching devicefrom the first to the second configuration,

wherein the catching device is biased towards the first configuration.

An aspect of the present invention relates to a method for actuating avalve of a downhole tool, the tool having a main bore corresponding tothe well bore and one or more fluid ports which are transverse to themain bore, the valve being actuatable to open the transverse ports, themethod comprising:

mounting a catching device within the main bore, the catching devicehaving a first configuration in which the device allows the passage ofan object dropped down the well bore and a second configuration in whichthe device catches the dropped object;

configuring the valve to open the transverse ports when the catchingdevice is at the second configuration;

dropping the object down the well bore;

switching the catching device from the first to the second configurationso that the dropped object is caught; and

biasing the catching device towards the first configuration.

An aspect of the present invention relates to a downhole system,comprising:

a tool string to be arranged within a wellbore;

a plurality of downhole actuators arranged along the tool string,wherein each downhole actuator comprises an indexing arrangement toprogress through the tool string towards an actuation site in apredetermined number of discrete steps of movement by passage of acorresponding number of actuation objects through the indexingarrangement; and

a plurality of downhole tools arranged along the tubing string, whereineach downhole tool is arranged to be actuated by at least one downholeactuator,

wherein at least two downhole tools are different.

Accordingly, a common form of a downhole actuator may be used within thetool system to operate various types of tool. Such an arrangement mayassist to minimize the requirement to provide bespoke actuation ofdifferent types of downhole tools. This may minimize complexities ofwellbore systems, and associated costs and reliability issues.

The downhole system may comprise a downhole actuator according to anyother aspect.

At least two downhole actuators may be initially configured to actuaterespective associated downhole tools by passage of a different number ofobjects. Such an arrangement may permit at least two tools to beactuated at different times or in a desired sequence.

In some embodiments at least two downhole actuators may be initiallyconfigured to actuate respective associated downhole tools by passage ofthe same number of objects.

Any sequence of operation of the downhole tools may be achieveddepending on the initial configuration of the actuators.

The downhole tool may comprise at least two tools of the same type.

The downhole tool may comprise at least two tools of a first type, andat least two tools of a second type.

The downhole system may comprise at least one downhole tool according toany other aspect.

At least one downhole tool may comprise a downhole valve.

At least one downhole tool may comprise a downhole sealing tool, such asa packer.

At least one downhole tool may comprise a catching arrangement, such asa catching arrangement which may be actuated to catch, and/or release,an object, such as an object used to operate one or more downholeactuators. At least one downhole tool may comprise a catchingarrangement according to any other aspect.

At least one downhole tool may comprise a fracturing tool, configured tofacilitate outflow of a fracturing fluid.

At least one downhole tool may comprise a flow control valve, such as aninflow control device (ICD).

At least one downhole tool may comprise a perforation gun.

In some embodiments the downhole system may comprise a first downholeactuator associated with a first downhole tool, and a second downholeactuator associated with a second downhole tool. The first downhole toolmay comprise a packer. The second downhole tool may comprise afracturing tool.

The first downhole actuator may be configured to actuate the firstdownhole tool upon passage of a first number of objects, and the seconddownhole actuator may be configured to actuate the second downhole toolupon passage of a second number of objects. In some embodiments thefirst number of objects may be lower than the second number of objects.

The downhole system may comprise first and second axially adjacentpackers, and a valve located intermediate said first and second packers.The valve may comprise or define a fracturing valve.

The downhole system may comprise a first downhole actuator associatedwith the first packer, a second downhole actuator associated with thesecond packer, and a third downhole actuator associated with thefracturing valve.

The third downhole actuator may be configured to actuate the fracturingvalve following passage of a greater number of objects than the firstand second downhole actuators require to actuate the respective firstand second packers.

The first and second downhole actuators may be configured to actuatetheir respective first and second packers upon passage of the samenumber of objects. Alternatively, the first and second downholeactuators may be configured to actuate their respective first and secondpackers upon passage of a different number of objects.

According to an aspect of the present invention there is provided adownhole method, comprising:

arranging a tool string within a wellbore, wherein the tool stringincludes a plurality of downhole actuators and a plurality of downholetools arranged along the tubing string, wherein each downhole tool isarranged to be actuated by at least one downhole actuator, and at leasttwo downhole tools are different;

arranging an indexing arrangement within each downhole actuator to beprogressed through the tool string towards an actuation site in apredetermined number of discrete steps of movement by passage of acorresponding number of actuation objects through the indexingarrangement; and

passing objects along the tool string to cause actuation of the downholetools.

According to an aspect of the present invention there is provided adownhole system, comprising:

a tool string;

a first downhole tool arranged in the tool string;

a first downhole actuator associated with the first downhole tool andbeing configured to actuate the first downhole tool in response to thepassage of a predetermined number of objects in a downstream direction;

a second downhole tool arranged in the tool string downstream of thefirst downhole tool;

a second downhole actuator associated with the second downhole tool andbeing configured to actuate the second downhole tool in response to thepassage of a predetermined number of objects in the downstreamdirection; and

a catching arrangement located downstream of the second downholeactuator and configured to selectively catch an object passing throughthe system in a downstream direction.

The first and second downhole actuators may be provided in accordancewith any other aspect.

In one embodiment at least one or both of the first and second actuatorsmay comprise an indexing arrangement, such as an indexing sleeve,arranged to progress through the tool string towards an actuation sitein a predetermined number of discrete steps of movement by passage of acorresponding number of actuation objects. Upon reaching the actuationsite the indexing arrangement may actuate a respective downhole tool.

One or both of the first and second tools may be provided in accordancewith any other aspect.

One or both of the first and second tools may comprise a fracturingtool.

In one embodiment at least one of the first and second downhole toolsmay comprise a valve member, such as a valve sleeve, configured to bemoved by an associated downhole actuator. The valve member may bemovable to selectively vary opening/closing of a fluid port within thetool string.

In one embodiment both the first and second downhole tools may comprisea valve member, such as a valve sleeve, configured to be moved by thefirst and second downhole actuators, respectively. Each valve member maybe movable to selectively vary opening/closing of a respective fluidport within the tool string.

In an embodiment where both the first and second downhole tools comprisea valve member for selectively opening a respective fluid port, thecatching arrangement may function to catch an object to divert flowwithin the tool string through the associated fluid ports when opened.In this way, only a single catching arrangement may be utilized toaccommodate the appropriate functionality of both the first and seconddownhole tools.

In some embodiments the downhole system may comprise a third or furtherdownhole tools and associated downhole actuators. The third or furtherdownhole tools may be located upstream of the catching arrangement.

The catching arrangement may be configurable from a free configurationin which an object is free to pass the catching arrangement, to acatching configuration in which a passing object may be caught. Thecatching arrangement may be reconfigured from its free to catchingconfiguration by the second downhole tool, for example by a valve memberof the second downhole tool. In one embodiment the catching arrangementmay be reconfigured by an associated downhole actuator.

The catching arrangement may comprise a catching sleeve.

The catching arrangement may comprise one or more radially movable seatmembers. The catching arrangement may be configurable from it freeconfiguration in which the seat members permit an object to pass throughthe tool string, to a catching configuration in which the seat memberscatch an object passing through the tool string.

When the catching arrangement is configured in its catchingconfiguration an object passing through the tool string may seat againstthe seat members and become caught.

According to an aspect of the present invention there is provided amethod for downhole actuation, comprising:

arranging first and second downhole tools along a tool string in awellbore;

arranging a first downhole actuator within the tool string to actuatethe first downhole tool in response to the passage of a predeterminednumber of objects in a downstream direction;

arranging a second downhole actuator within the tool string to actuatethe second downhole tool in response to the passage of a predeterminednumber of objects in the downstream direction;

arranging a catching arrangement downstream of the first and seconddownhole actuator; and

passing a predetermined number of objects along the tool string toactuate both the first and second tools; and

configuring the catching arrangement to catch an object after the firstand second tools have been actuated.

A downhole tool according to a further aspect of the inventioncomprises: a housing; an actuatable member; a catching arrangement; anda coupling arrangement configured to provide a rotary coupling betweenthe actuatable member and the catching arrangement and/or the housingand configured to permit relative axial movement of at least one of theactuatable member and the catching arrangement relative to the housing.

Embodiments of the present invention beneficially provide a downholetool having a coupling which transmits rotational movement of onecomponent of a downhole tool, such as the actuatable member, to at leastone of the other components of the downhole tool, such as the catchingarrangement and/or the housing, while permitting axial movement betweenthe components.

The catching arrangement may be arranged to be axially moved by theactuatable member.

The transmission of rotational movement may provide a rotational lockfor example. Alternatively, or additionally, the transmission ofrotational movement may ensure rotational alignment of the actuatablemember and the catching arrangement and/or the housing.

The coupling arrangement may be configured to transmit a force betweenthe actuatable member and the catching arrangement and/or the housing.

The coupling arrangement may be configured to transmit an axial forcefrom the actuatable member to the catching arrangement.

The coupling arrangement may be configured to transmit an axial forcefrom at least one of the catching arrangement and the housing.

The coupling arrangement may define, comprise or form part of a timingarrangement of a downhole tool or system, such as the timing arrangementdefined in other aspects of the invention.

The coupling arrangement may be configured to permit relative axialmovement of the actuatable member and the housing.

The coupling arrangement may be configured to permit relative axialmovement of the actuatable member and the catching arrangement.

The coupling arrangement may be configured to permit axial movement ofthe actuatable member and catching arrangement relative to the housing.

The actuatable member may, for example, comprise a valve member and inparticular embodiments, the actuatable member may comprise a valvesleeve.

The catching arrangement may comprise a catching member and inparticular embodiments the catching arrangement may comprise a catchingsleeve. The catching arrangement may be movable between a freeconfiguration and a catching configuration.

Axial movement of the actuatable member, e.g. the valve sleeve, may movethe catching arrangement, e.g. the catching sleeve, from the freeconfiguration to the catching configuration.

The coupling arrangement may be of any suitable form and construction.

The coupling arrangement may comprise a key.

The key may comprise a single key element.

The key may be disposed in a recess or groove in the actuatable member.

Alternatively, and in particular embodiments, the key may comprise aplurality of key elements. The key elements may be located about theactuatable member, and may be circumferentially spaced around theactuatable member.

The coupling arrangement may comprise a slot or groove in the housing.

The coupling arrangement may comprise a single slot or groove in thehousing.

The coupling arrangement may comprise a single key element extendinginto or through the slot or groove in the housing.

Alternatively, the coupling arrangement may comprise a plurality ofslots or grooves in the housing.

The coupling arrangement may comprise a plurality of key elements, eachextending into or through a corresponding slot or groove.

In embodiments where the coupling arrangement comprises a plurality ofslots or grooves in the housing, the slots or grooves may becircumferentially arranged.

The coupling arrangement may comprise a slot or groove in the catchingarrangement.

The coupling arrangement may comprise a single slot or groove in thecatching arrangement.

Alternatively, the coupling arrangement may comprise a plurality ofslots or grooves in the catching arrangement.

In embodiments where the coupling arrangement comprises a plurality ofslots or grooves in the catching arrangement, the slots or grooves maybe circumferentially arranged.

The key may be disposed in the slot or recess.

In particular embodiments, the tool may comprise a plurality of keyelements, each of the key elements extending through a slot in thecatching arrangement and into a groove in the housing.

The catching arrangement slot or groove and the housing slot or groovemay at least partially axially overlap.

The tool may be configured to provide a positive indication that anevent, such as an activation event, has occurred. The activation eventtool may comprise opening a port. The positive indication may comprise apressure drop.

An aspect of the present invention relates to a downhole actuator,comprising:

a tubular housing which includes an indexing profile on an inner surfacethereof; and

an indexing sleeve mounted within the housing and comprising an engagingarrangement including first and second axially spaced engagement memberswhich cooperate with the indexing profile of the housing to besequentially engaged by an actuation object passing through a centralbore of the indexing sleeve to drive the indexing sleeve one discretestep of movement through the housing towards an actuation site.

The indexing sleeve may be arranged to progress within the housingtowards the actuation site in a predetermined number of discrete stepsof movement by passage of a corresponding number of actuation objectsthrough the central bore of the indexing sleeve.

The downhole actuator may be configured to permit the indexing sleeve tobe disabled, such that the indexing sleeve, when disabled, may not movedupon passage of an actuation object.

The indexing sleeve may be configured to be disabled at the actuationsite.

The indexing sleeve may be configured to function as a latch for adownhole tool when said indexing sleeve is disabled at the actuationsite.

The indexing sleeve may be configured to be disabled at a locationremote from the actuation site.

The indexing profile may facilitate the indexing sleeve to becomedisabled.

The indexing profile may comprise a disabled region, wherein alignmentof the indexing sleeve with the disabled region of the indexing profilemay permit the indexing sleeve to become disabled.

The indexing profile may comprise a disabled region which coincides withthe actuation site of the actuator.

The indexing profile may comprise a disabled region which is remote fromthe actuation site.

The indexing sleeve may be configured to be moved towards the remotedisabled region by use of a shifting tool.

The indexing sleeve may define a shifting profile to facilitateengagement by a shifting tool.

The indexing profile may define a disabled region at opposing axial endsof said indexing profile.

The indexing profile of the housing may comprise a plurality of annularrecesses arranged longitudinally along the housing. The annular recessesmay provide a variation of the inner diameter along the length of thehousing, such that movement of the indexing sleeve through the housingmay permit the radial position of first and second engagement members tobe varied.

The indexing sleeve may be configured to cooperate with the indexingprofile of the housing such that during movement of the indexing sleevelongitudinally through the housing each engagement member may besequentially received within adjacent annular recesses, such that whenreceived within a recess an engagement member may be positioned radiallyoutwardly and extended from the central bore of the indexing sleeve, andwhen positioned intermediate adjacent recesses an engagement member maybe positioned radially inwardly and thus retracted into the central boreof the indexing sleeve and thus presented into a path of travel of anactuation object through the indexing sleeve.

At least one pair of annular recesses may be arranged at a differentaxial spacing than the first and second engagement members.

The indexing profile may comprise multiple annular recesses arrangedlongitudinally along the housing at a common axial separation or pitch.

The indexing profile may comprise at least one pair of annular recesseswhich are arranged at an axial spacing which is equivalent to the axialspacing of the first and second engagement members.

The indexing sleeve may be configured to become disabled when the firstand second engagement members are received within a pair of annularrecesses which are arranged at the same axial spacing.

One axial end region of the indexing profile may comprise a pair ofannular recesses provided at an axial spacing which is equivalent to theaxial spacing of the first and second engagement members.

Opposing axial end regions of the indexing profile may comprise a pairof annular recesses with an axial spacing which corresponds to the axialspacing of the first and second engagement members of the indexingsleeve.

The first and second engagement members may be arranged relative to eachother to permit only a single actuation object to be positionedtherebetween.

The relative arrangement between the first and second engagement membersmay be selected in accordance with an actuation object which is utilizedto actuate and move the indexing sleeve a discrete step through thehousing.

The relative arrangement between the first and second engagement membersmay be selected in accordance with the geometry of an actuation objectwhich is utilized to actuate and move the indexing sleeve a discretestep through the housing.

The relative arrangement between the first and second engagement membersmay be related to an axial separation of the first and second engagementmembers.

The axial separation of the first and second engagement members may beless than or equal to twice the width of an actuation object.

The actuation object may comprise a ball, and the axial separation ofthe first and second engagement members may be less than or equal totwice the diameter of the ball.

The relative arrangement between the first and second engagement membersmay be related to a permitted radially inward movement of the engagementmembers into the central bore.

The first and second engagement members may define a confinement regiontherebetween, for temporarily accommodating an actuation object duringpassage of said object through the indexing sleeve.

The confinement region may be configured to permit only a singleactuation object to be accommodated therein at any time.

A final discrete step of linear movement of the indexing sleeve maypermit said sleeve to initiate actuation of an associated downhole tool.

The indexing sleeve may be configured to completely actuate a downholetool upon the indexing sleeve reaching the actuation site.

The indexing sleeve may be configured to partially actuate a downholetool upon the indexing sleeve reaching the actuation site.

The indexing sleeve may cooperate with the indexing profile of thehousing to be moved in a discrete step in any direction of travel of apassing actuation object.

The indexing sleeve may be movable in reverse directions by discretelinear movement steps in accordance with the direction of travel of anactuation object.

The indexing sleeve may be reconfigurable, in situ, to permit sequentialengagement of the first and second engagement members in reversedirections of a passing actuation object. Said in situ reconfigurationmay be achieved by an initial passage of an actuation object in areverse direction.

The first and second engagement members may be arranged on the indexingsleeve to be selectively moved radially by cooperation with the indexingprofile on the housing during movement of the indexing sleeve throughthe housing.

The radial movement of the first and second engagement members mayselectively extend and retract said members relative to the central boreof the indexing sleeve to permit the engagement members to beselectively presented into a path of travel of an actuation objectthrough the central bore of the indexing sleeve to allow said sleeve tobe driven through the housing by one discrete step.

The radial movement of the first and second engagement members maysequentially present said members into the central bore and a path oftravel of an actuation object to permit said object to sequentiallyengage the engagement members to drive the indexing sleeve through thehousing by one discrete step.

The radial position of the first and second engagement members may becyclically varied by cooperation with the indexing profile duringmovement of the indexing sleeve through the housing.

The radial position of the first and second engagement members is variedout of phase relative to each other by cooperation with the indexingprofile during movement of the indexing sleeve through the housing.

One or both of the first and second engagement members may be biased ina preferred radial direction.

One or both of the first and second engagement members may be biased ina radially outward direction to be retracted from the central bore ofthe indexing sleeve.

The downhole actuator may comprise first and second fingers whichsupport a respective one of the first and second engagement members ondistal ends of said fingers.

The fingers may be deformable to permit the engagement members to moveradially upon cooperation with the indexing profile.

The first and second fingers may extend in opposing directions, forexample opposing axial directions.

The engaging arrangement may comprise an array of first engagementmembers arranged circumferentially around the indexing sleeve.

Each first engagement member may be mounted on a respective firstfinger.

The engaging arrangement may comprise an array of second engagementmembers arranged circumferentially around the indexing sleeve.

Each second engagement member may be mounted on a respective secondfinger.

The indexing sleeve may be configured to be moved a discrete movementstep when an actuation object is driven by a fluid flow at a flow rateof between 5 and 70 barrels per minute.

The first and second engagement members may each define a seatarrangement for allowing an actuation object to engage and seat againstduring passage through the indexing sleeve.

The first and second engagement members may define a seat arrangement onopposing axial sides thereof to permit an actuation object to engage andseat against the engagement members in reverse directions of movement.

One or both of the first and second engagement members may define aconvex seat surface to be engaged by an object.

The indexing sleeve may be arranged to be advanced along the housing ina discrete movement step by sequential impact of an actuation objectagainst the first and second engagement members.

The indexing sleeve may be configured to be advanced along the housingin a discrete step by a differential pressure applied between upstreamand downstream sides of the indexing sleeve. The differential pressuremay be created upon engagement of the object with each of the first andsecond engagement members.

The downhole actuator may comprise a monitoring arrangement formonitoring the passage of an actuation object through the indexingsleeve.

The monitoring arrangement may comprise an acoustic monitoringarrangement configured to identify an acoustic signal generated byimpact of an actuation object against the first and second engagementmembers.

The monitoring arrangement may comprise a pressure monitoring systemconfigured to identify a pressure variation generated during engagementof an actuation object with the first and second engagement members.

The downhole actuator may comprise an anti-rotation arrangement providedbetween the indexing sleeve and the housing.

One of the housing and the indexing sleeve may comprise a key, and theother of the housing and the indexing sleeve may comprise a key-wayconfigured to receive said key.

The downhole actuator may comprise a stand-off arrangement radiallypositioned between the housing and the indexing sleeve to define aradial separation gap between the housing and the indexing sleeve.

The width of the radial separation gap may be provided at a preferredminimum gap width.

The preferred minimum gap width may be selected in accordance with thedimension of a particle or particles carried by a fluid communicatedthrough the actuator.

The preferred minimum radial gap width between the housing and indexingsleeve may be at least twice the mean particle diameter of particlescarried by a fluid communicated through the actuator.

The stand-off arrangement may align the indexing sleeve substantiallyconcentrically within the housing.

The stand-off arrangement may comprise at least one rib positionedbetween the housing and the indexing sleeve.

The stand-off arrangement may comprise a plurality of circumferentiallyarranged ribs positioned between the housing and the indexing sleeve.

The indexing sleeve may be configured to be initially positioned at anydesired location along the indexing profile to determine the requirednumber of actuation objects, and thus required discrete steps ofmovement, to drive the indexing sleeve to the actuation site.

The housing may be modular and may comprise multiple housing modulesconnected together to collectively define the housing. Individualhousing modules may define a portion of the indexing profile, such thatwhen the individual modules are connected together the entire indexingprofile may be formed.

Adjacent housing modules may be secured together such that an indexingprofile feature may be defined at an interface therebetween.

Adjacent housing modules may each define a portion of a profile featuresuch that when the adjacent housing modules are connected the completeprofile feature may be formed.

The indexing sleeve may be configured to engage an actuatable member ofa downhole tool.

An aspect of the present invention relates to a method for downholeactuation, comprising:

arranging a downhole actuator according to any preceding claim relativeto a downhole tool;

passing a predetermined number of actuation objects through the downholeactuator to cause the indexing sleeve to move in a corresponding numberof discrete steps of movement through the housing towards an actuationsite to actuate the downhole tool.

The method may comprise disabling the indexing sleeve within thehousing, such that the indexing sleeve, when disabled, may not movedupon passage of an actuation object.

The method may comprise preventing more than one actuation object to bepositioned between the first and second engagement members of theindexing sleeve at any one time.

An aspect of the present invention relates to a downhole actuator,comprising:

a tubular housing; and

an indexing sleeve mounted within the housing and comprising an engagingarrangement which is engageable by an actuation object passing through acentral bore of the indexing sleeve to drive the indexing sleeve onediscrete step of movement through the housing towards an actuation site;

wherein the indexing sleeve is configured to be disabled when located ata disable region within the housing, such that the indexing sleeve, whendisabled, is not moved upon passage of an actuation object.

An aspect of the present invention relates to an inspection apparatusfor use in inspecting or determining the position of an indexing sleevewithin a housing of a downhole actuator, comprising:

an inspection object configured to engage the indexing sleeve;

an elongate member connected to the engagement member and configured tobe inserted into the housing from one end thereof to engage theinspection object with the indexing sleeve with a portion of theelongate member extending from the housing; and

a visual reference provided on the elongate member to provide a userwith a visual indication for use in determining the location of theindexing sleeve within the housing.

An aspect of the present invention relates to an indexing sleeve for usein a downhole actuator, comprising:

an engaging arrangement including first and second axially spacedengagement members for cooperating with an indexing profile of a housingto be sequentially engaged by an actuation object passing through acentral bore of the indexing sleeve to drive the indexing sleeve onediscrete step of movement through the housing towards an actuation site.

An aspect of the present invention relates to a downhole system,comprising:

a downhole actuator according to any other aspect; and

a downhole tool arranged relative to the downhole actuator,

wherein the downhole actuator is operable to actuate the downhole tool.

The downhole system may comprise a plurality of downhole actuators and aplurality of downhole tools, wherein each actuator may be configured toactuate at least one tool.

At least two downhole actuators may be configured to actuate anassociated downhole tool upon passage of a different number of actuationobjects.

At least one downhole tool may comprise a valve.

At least one downhole tool may comprise a fracturing valve.

At least one downhole tool may comprise a packer.

An aspect of the present invention relates to a method for downholeactuation, comprising:

providing an indexing arrangement defining a central bore and includingan engaging arrangement including first and second engagement members;

locating the indexing arrangement within a housing defining an indexingprofile configured to cooperate with the first and second engagementmembers of the indexing arrangement to cause said engagement members tobe selectively moved radially relative to the central bore of theindexing arrangement;

locating the indexing arrangement and housing in a wellbore; and

delivering an object through the indexing arrangement to selectivelyengage at least one of the first and second engagement members to drivethe indexing arrangement at least one discrete movement step towards anactuation site.

Features defined in relation to one aspect may be provided incombination with any other aspect.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects of the present invention will now be described,by way of example only, with reference to the accompanying drawings, inwhich:

FIG. 1 is a diagrammatic view of a wellbore system which includes acompletion/fracturing string including a number of fracturing toolsaccording to an embodiment of the present invention;

FIG. 2 is a longitudinal cross-sectional view of a downhole tool,specifically a downhole fracturing tool, according to an embodiment ofthe present invention;

FIG. 3 is a perspective view of an indexing sleeve of the tool of FIG.2;

FIGS. 4A to 4E illustrate a sequence of operation of the indexing sleeveof the tool in FIG. 2 over one discrete linear movement step by passageof a single actuation object;

FIG. 5 is an enlarged view of the tool of FIG. 2 in the region of avalve and ball catching arrangement;

FIGS. 6A to 6D are perspective views of a catching sleeve component ofthe tool of FIG. 2, shown in different stages of manufacture;

FIGS. 7A to 7E illustrate a sequence of operation by an actuation objectto reconfigure the tool into an operational state;

FIG. 7F provides an enlarged view of region F in FIG. 7E:

FIG. 7G provides an enlarged view of region G in FIG. 7E;

FIGS. 7H and 7I illustrate a subsequent sequence of operation to permitan actuation object to be released from the tool;

FIGS. 8A, 8B and 8C illustrate individual fracturing tools to bearranged within a completion/fracturing string, such as shown in FIG. 1,wherein each tool is provided with the respective indexing sleeves in adifferent commission position;

FIG. 9 illustrates the tool of FIG. 2 in combination with an inspectionapparatus for use in determining the position of an indexing sleeve

FIG. 10 is a cross-sectional view of a downhole tool in accordance withan embodiment of the present invention;

FIG. 11 is a cross-sectional view in the region of an indexing sleeve ofa downhole tool in accordance with an embodiment of the presentinvention, and also provides a diagrammatic representation of a shiftingtool for shifting the indexing sleeve;

FIG. 12 is a cross-sectional view of a downhole tool in accordance withan embodiment of the present invention, wherein the tool includesassociated sealing arrangements;

FIG. 13 is an enlarged view of a sealing arrangement of FIG. 12;

FIGS. 14A and 14B show a seal arrangement of FIG. 12 in a run-in and setconfiguration, respectively;

FIGS. 15A to 15D are cross-sectional views of a portion of a downholetool in accordance with a further embodiment of the present invention,shown in different stages of operation;

FIGS. 16A to 16E are cross-sectional views of a portion of a downholetool in accordance with a further embodiment of the present invention,shown in different stages of operation;

FIGS. 17A and 17B are schematic illustrations of a downhole system inaccordance with an embodiment of the present invention, shown indifferent stages of operation;

FIGS. 18A and 18B are schematic illustrations of a downhole system inaccordance with an alternative embodiment of the present invention,shown in different stages of operation;

FIGS. 19A to 19D are schematic illustrations of a downhole system inaccordance with a further embodiment of the present invention, shown indifferent stages of operation;

FIG. 20A is a schematic illustration of a downhole system in accordancewith an further alternative embodiment of the present invention; and

FIG. 20B is a lateral cross-sectional view of the system of FIG. 20A,taken through line B-B.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1 provides a diagrammatic illustration of a well bore system 10including a drilled borehole 12 which intercepts a subterraneanreservoir or formation 14. The formation 14 may contain hydrocarbons tobe produced to surface via the well system 10. Alternatively, oradditionally, the subterranean formation 14 may define a target forreceiving a fluid injected from surface via the wellbore system 10, forexample for increasing formation pressure to improve production ofhydrocarbons from the formation 14 or a neighboring formation, forsequestration purposes, or the like.

Following drilling of the borehole 12, or following a period ofproduction/injection, the formation 14 may require to be stimulated ortreated to permit improved production or injection rates to be achievedor restored. Known stimulation techniques include hydraulic fracturingwhich involves injecting a fracturing fluid into the formation at highpressure and/or flow rates to create mechanical fractures within thegeology. These fractures may increase the effective near-wellborepermeability and fluid connectivity between the formation and wellbore.The fracturing fluid may carry proppant material, which functions toprop open the fractures when the hydraulic fracturing pressure has beenremoved. Matrix stimulation provides a similar effect as hydraulicfracturing. This typically involves injecting a chemical such as anacid, for example hydrochloric acid, into the formation 14 to chemicallycreate fractures or wormholes in the geology. Such matrix stimulationmay have application in particular geology types, such as in carbonatereservoirs.

In most stimulation or treatment regimes it is necessary to provide theability to inject a treatment fluid into the formation via wellboretools and infrastructure. Embodiments of the present invention permitsuch injection to be achieved. In this respect, a tubular string 16extends through the borehole 12 of FIG. 1, wherein the string 16comprises a plurality of fracturing tools 18 according to the presentinvention distributed along its length at a desired interval spacing.Each tool 18 includes a plurality of circumferentially arranged ports20, which are initially closed. Further, each tool 18 includes or isassociated with a downhole actuator (not shown in FIG. 1) which isoperable to actuate the tool 18 to open the associated ports 20 to allowinjection of a treating fluid, such as a fracturing fluid or acid, fromthe string 16 into the surrounding formation 14 to create fractures 22.As will be described in more detail below, each tool 18 is operated byactuation objects, such as balls, which are delivered through the string16 from surface.

The tools 18 are capable of being actuated in a desired sequence, thusallowing the formation 14 to be treated along the length of the wellbore12 in stages. Such ability to actuate the tools 18 sequentially may beachieved via the associated downhole actuator, as will be described infurther detail below. In the particular embodiment shown in FIG. 1 thetools 18 are arranged to be actuated in an uphole sequence or direction.This is shown in FIG. 1 in which the lowermost illustrated tool 18 a haspreviously been actuated, with an adjacent tool 18 b on the uphole sideshown in an actuated state with fracturing fluid from the opened ports20 b being directed into the formation 14 in the direction of arrows 24.Once appropriate fracturing has been achieved via tool 18 b, the nextuphole tool 18 c may then be actuated. However, in other embodiments anysequence of operation of the tools may be achieved.

In the exemplary embodiment shown the tools 18 include optional annularseals 26 a, 26 b (shown energized on actuated tool 18 b) on opposingaxial sides of the ports 20 b. When the seals 26 a, 26 b are energizedthey provide isolation of an annular region 28 around the tools 18, thusfocusing the fracturing fluid into the formation 14, which may assistwith improving geological penetration. The seals 26 a, 26 b may beactuated or energized by the action of the fracturing fluid beinginjected from the tool ports 20. In some embodiments the seals 26 a, 26b may comprise cup seals.

A cross sectional view of a downhole tool 18, according to an exemplaryembodiment of one or more aspects of the present invention is shown inFIG. 2. The tool 18 includes an actuator portion 30, provided accordingto an embodiment of an aspect of the present invention. The tool 18 alsoincludes a tool portion 32 located on the downhole side of the actuatorportion 30, wherein the tool portion 32 is provided according to anembodiment of an aspect of the present invention. In the embodimentshown, the actuator portion 30 and tool portion 32 and provided togetherto define a complete downhole tool 18. However, it should be recognizedthat the actuator and tool portions 30, 32 may be provided independentlyof each other. For example, the actuator portion 30 may be used toactuate any other downhole tool, such as a packer, ICD or the like.Further, the tool portion 32 may be actuated by any other suitableactuator arrangement.

The downhole tool 18 comprises a housing 34 which defines a central bore35 and extends between an uphole connector 36 and a downhole connector38. The connectors 36, 38 facilitate connection of the tool 18 withinthe tubular string 16 (FIG. 1).

Fluid ports 20 are provided radially through a wall of the housing 34 inthe region of the tool portion 32, wherein the ports 20, when opened,facilitate outflow of a fluid from the central bore 35 of the housing34. The tool portion 32 includes a valve member in the form of a sleeve40 which is movable axially along the housing 34 from a closed positionin which the sleeve 40 blocks or closes the ports 20, as shown in FIG.2, to an open position. Movement of the sleeve 40 towards its openposition is achieved by the associated actuator portion 30, as describedbelow.

The tool portion 32 further includes a catching sleeve 41 locateddownhole of the valve sleeve 40. The catching sleeve 41 illustrated isan embodiment of an aspect of the present invention. Although thecatching sleeve 41 is illustrated as part of the present downhole tool,it should be understood that the catching sleeve 41 may be used in anyother downhole tool.

The catching sleeve 41 is movable from a free configuration, as shown inFIG. 2, in which a ball 48 may freely pass, to a catching configurationin which a ball 48 may be caught. In the present embodiment, thecatching sleeve may function to catch a ball and establish diversion ofany fluid from the central bore 35 outwardly through the fluid ports 20when open. Further, in the present embodiment the catching sleeve 41 isoperated to move to its catching configuration by movement of the valvesleeve 40 towards its open configuration. The form and operation of thevalve sleeve 40 and catching sleeve 41 will be described in furtherdetail below.

The actuator portion 30 defines an indexing profile 42 provided on theinner surface of the housing 34. The indexing profile 42 includes aplurality of axially spaced annular recesses 44 formed in the innersurface of the housing 34. An indexing sleeve 46 is mounted within thehousing 34 and is configured to cooperate with the indexing profile 42to be driven in a number of discrete linear movement steps through thehousing 34 by passage of a corresponding number of actuation objects,specifically balls 48 in the present embodiment. The indexing sleeve 46illustrated is an embodiment of an aspect of the present invention. Theindexing sleeve 46 is driven in discrete movement steps until reachingan actuation site within the tool 18, where the indexing sleeve 46engages and moves the valve sleeve 40 in a downhole direction to openthe ports 20.

A perspective view of the indexing sleeve 46 removed from the housing 34is shown in FIG. 3, reference to which is additionally made.

The indexing sleeve 46 includes a tubular wall structure 49 whichdefines a central bore 50 corresponding with the central bore 35 of thehousing 34. The central bore 50 is sized to permit an actuation object,specifically balls 48 to pass therethrough.

The indexing sleeve 46 also includes first and second circumferentialarrays of engagement members 52, 54 which are arranged such that thearray of first engagement members 52 are axially spaced apart from thearray of second engagement members 54. The engagement members arearranged within slots 56, 58 formed through the wall structure 49. Aswill be described in more detail below, the arrays of engagement members52, 54 cooperate with the indexing profile 42 of the housing 34 to besequentially engaged by a passing ball 48 to drive the indexing sleeve46 one discrete linear movement step. More specifically, the first andsecond arrays of engagement members 52, 54 are arranged to be movedradially within their associated slots 56, 58 such that each array ofengagement members 52, 54 is moved in an alternating or out of phasemanner relative to the other array of engagement members 52, 54 bycooperation with the indexing profile 42 during movement of the indexingsleeve 46 through the housing 34. Such alternating radial movementalternately moves the first and second arrays of engagement members 52,54 radially inwardly and into the central bore 50 of the indexing sleeve46, to thus be sequentially engaged by a passing ball 48. In this way, apassing ball 48 may engage the engagement members 52, 54 of one of thefirst and second arrays to move the indexing sleeve 46 a portion of adiscrete movement step, and then subsequently engage the engagementmembers 52, 54 of the other one of the first and second arrays tocomplete the discrete movement step of the indexing sleeve 46.

The engagement members 52, 54 are mounted on the distal end ofrespective collet fingers 60 which are secured at their proximal ends tothe tubular wall structure 49. The collet fingers 60 are resilientlydeformable to facilitate radial movement of the engagement members 52,54 by cooperation with the indexing profile 42. In the presentembodiment the collet fingers 60 are unstressed when the engagementmembers 52, 54 are positioned radially outwardly and thus removed fromthe central bore 50. As such, the collet fingers 60 must be positivelydeformed by appropriate cooperation between the engagement members 52,54 and the indexing profile 42 to move the engagement members 52, 54radially inwardly into the central bore 50 to permit engagement by aball 48. In such an arrangement, the collet fingers 60 may function tobias the engagement members 52, 54 in a direction to move radiallyoutwardly from the central bore 50.

In the embodiment shown each slot 56, 58 of the indexing sleeve 46accommodates two respective engagement members 52, 54. Further, theslots 56, 58 are defined between respective elongate ribs 62, 64. Eachrib 62, 64 includes a spline feature or key 66 which are received incorresponding longitudinally extending slots or key-ways (not shown inthe drawings) formed in the housing 34. Engagement between the keys 66and the longitudinal slots or key-ways may function to rotationally lockthe indexing sleeve 46 relative to the housing 34, while stillpermitting movement of the indexing sleeve 46 linearly through thehousing 34. Such an arrangement may facilitate milling of the indexingsleeve 46, if ever required.

In some embodiments the indexing sleeve 46 may include a stand-offarrangement, permitting the indexing sleeve 46 to be mounted within thehousing 34 with a desired clearance gap therebetween. For example, insome cases the keys 66 shown in FIG. 3 may in fact function to directlyengage the inner surface of the housing 34, thus providing a stand-offclearance at least as large as the thickness of the keys 66. Providingsuch a stand-off with a clearance gap between the housing 34 and theindexing sleeve 46 may assist to minimize binding of the indexing sleeve46 within the housing 34, for example by the accumulation of debris,such as proppant material.

A sequential operation of the indexing sleeve 46 to move one discretestep by passage of a ball 48 will now be described in detail withreference to FIGS. 4A to 4E, which each illustrate a portion of the tool18 in the region of the actuator portion 30.

In the illustrated sequence the ball 48 travels in the direction ofarrow 70, and thus functions to move the indexing sleeve 46 in the samedirection. The direction of travel of the ball 48 in the present exampleis in the downhole direction. However, as will be described in moredetail below, the indexing sleeve 46 may also be moved by passage of aball in an opposite, uphole direction. As such, generally, the directionof travel of the ball 48 may be considered as in a downstream direction.

Prior to initiation of a discrete movement step, as shown in FIG. 4A,the indexing sleeve 46 is positioned within the housing 34 such that theengagement members 52 of the first array, which may be considered anupstream array, are positioned radially inwardly and thus presented intothe central bore 50, whereas the engagement members 54 of the secondarray, which may be considered a downstream array, are positionedradially outwardly, and in fact received within an annular recess 44 a.Such positioning of the engagement members 52, 54 is achieved by therelative axial spacing of the engagement members 52, 54 and the axialspacing, or pitch, of the annular recesses 44. That is, the axialspacing between the engagement members 52, 54 differs from, andspecifically is larger than that of adjacent annular recesses 44. Assuch, when the engagement members 52, 54 of one of the first and secondarrays are received within an annular recess 44 and outwardly positionedrelative to the central bore 50, the engagement members 52, 54 of theother one of the first and second arrays will be positioned intermediateadjacent recesses 44 and thus positioned inwardly relative to the bore50. Movement of the indexing sleeve 46 through the housing thereforepermits the radial position of the engagement members 52, 54 to becyclically varied, permitting sequential engagement by a ball.

When the ball 48 reaches the indexing sleeve 46 the ball 48 will seatagainst the first or upstream array of engagement members 52, as shownin FIG. 4A, causing the indexing sleeve 46 to begin to move, as shown inFIG. 4B. Such movement will cause the first array of engagement members52 to eventually become aligned with a recess 44 b, and thus movedradially outwardly from the central bore 50, allowing the ball 48 topass, as shown in FIG. 4C. However, at the same time the engagementmembers 54 of the second array will be deflected radially inwardly, tobe positioned within the central bore 50, by misalignment with anannular recess 44. In this respect, in the embodiment shown the recesses44 and the engagement members 52, 54 define corresponding ramped ortapered sides, for example of around 45 degrees, to facilitate or assistinteraction during relative axial movement of the indexing sleeve 46through the housing 34. As the engagement members 54 of the second arrayare now positioned radially inwardly the ball 48 will become seatedagainst these engagement members 54, thus continuing to drive theindexing sleeve 48, as shown in FIG. 4D.

Eventually, the engagement members 54 of the second array will againbecome aligned with an annular recess 44 c, thus permitting the ball 48to be released and continue in the downstream direction, as shown inFIG. 4E. At the same time, the engagement members 52 of the first arraywill be positioned intermediate adjacent annular recesses 44 a, 44 b,becoming radially inwardly deflected, and positioned to be engaged by asubsequent ball.

The ball 48 may drive the indexing sleeve 46 primarily by impact againstthe engagement members 52, 54 when positioned within the bore 50. Thatis, the momentum of the ball 48 passing through the indexing sleeve 46may drive said sleeve 46.

Alternatively, or additionally, the ball 48 may permit the indexingsleeve 46 to be driven by a pressure differential between upstream anddownstream sides of the indexing sleeve 46. For example, the ball 48 maybe driven by a fluid flow, and when the ball 48 seats against theengagement members a flow restriction may be created, which may permit aback pressure to be established, thus providing a desired pressuredifferential between upstream and downstream sides of the indexingsleeve 46. The flow restriction may be provided between the points ofengagement of the ball 48 with individual engagement members 52, 54.Alternatively, or additionally, the flow restriction may be achieved bydiversion of flow between the indexing sleeve and the housing 34 whenthe ball is seated against the engagement members 52, 54.

The use of a pressure differential to drive the indexing sleeve 46 maypermit monitoring of the progress of the ball 48 to be achieved. Forexample, a monitoring system 72 may be provided which monitors thevariation in pressure as the ball 48 progresses through the indexingsleeve. Such pressure variations may be associated with the particularpositioning of the ball 48, which may provide useful information to anoperator. Such an arrangement may be advantageous in cases wheremultiple actuators are provided in series within a tubular string, asillustrated in FIG. 1. In an alternative embodiment, an acousticmonitoring system may be used, which monitors acoustic signals generatedduring interaction between the ball 48 and the indexing sleeve 46.

As noted above, the indexing sleeve is operable to be driven by a ballin opposing directions. Such an arrangement will now be exemplified withreference to FIG. 4E. In FIG. 4E the indexing sleeve 46 is positionedsuch that the first and second arrays of engagement members 52, 54 willbe sequentially engaged by a ball passing in a downhole direction. Thatis, the first array of engagement members 52 are positioned radiallyinwardly to be first engaged by a passing ball 48, while the secondarray of engagement members 54 are positioned radially outwardly. Whenin such a configuration, in the event of the ball 48 now travelling inan opposite, uphole direction, the ball 48 will pass the second array ofengagement members 54 (which will now become the upstream engagementmembers), and will engage the first array of engagement members 52(which will now become the downstream engagement members). Uponengagement with the first array of members 52 the indexing sleeve 46will be driven in an uphole direction until the first array of members52 become aligned with and received into the annular recess 44 b,permitting the ball 48 to be released and continue to travel in theuphole direction. At the same time, the second array of engagementmembers 54 will become misaligned with a recess 44 and thus movedradially inwardly. Thus, when in this reconfigured position the firstand second arrays of engagement members 52, 54 may now be sequentiallyengaged with a further ball passing in the uphole direction. As such, afirst ball passing in the uphole direction may reconfigure the indexingsleeve 46 to permit sequential engagement of the members 52, 54 by asubsequent passing ball.

In the exemplary wellbore system of FIG. 1 a number of tools 18 arearranged in series and configured to be actuated in a desired sequence.Such a desired sequence may be achieved by appropriate initialpositioning of the indexing sleeve 46 in each tool 18, such that thetools 18 are operated in response to the passage of a different numberof balls. Such ability to create a system which allows a desiredactuation sequence to be achieved based on the initial positioning ofrespective indexing sleeves will be described in further detail below.However, as the sequential operation of individual tools 18 may bereliant on passage of individual balls, it is important that each ballis registered upon passing through an indexing sleeve and reliably movesthe indexing sleeve a required discrete step. If a ball were to passwithout driving an indexing sleeve a corresponding discrete step thenthis may upset a desired actuation sequence. The present inventors haveidentified a potential for such ball passage without registering a countif two balls were ever to pass through an indexing sleeve in quicksuccession. If such an occasion were not addressed a trailing ball couldpotentially pass behind a leading ball without registering correspondingseparate discrete movement steps.

In the present embodiment the first and second arrays of engagementmembers 52, 54 are arranged relative to each other (specifically theaxial spacing of the members 52, 54) to permit only a single ball 48 tobe positioned therebetween at any time. As such, the axial regionbetween the first and second arrays of engagement members 52, 54 maydefine a ball trap. As shown in FIG. 4C, when the ball 48 initiallyenters this ball trap region between the first and second arrays ofengagement members 52, 54, the ball 48 will engage the members 54 of thesecond array. While in this position the members 52 of the first arrayare positioned radially outwardly. However, any subsequent or trailingball arriving at the indexing sleeve 46 at this time will not bepermitted to progress due to engagement with the ball 48 which ispositioned within the ball trap. As the indexing sleeve 46 progressesthe members 54 of the second array will eventually move radiallyoutwardly and thus permit the ball to be released, as shown in FIG. 4E.However, at the same time the members 52 of the first array will bemoved radially inwardly and thus will prevent progression of anytrailing ball, at least without the trailing ball now acting to drivethe indexing sleeve 46 a corresponding discrete movement step.

The tool portion 32 of the downhole tool 18 will now be described infurther detail with reference to FIG. 5, which is an enlarged view ofthe tool 18 of FIG. 2 in the region of tool portion 32. The tool portion32 is illustrated in an initial configuration, with the valve sleeve 40in a closed position and the catching sleeve 41 in a free configuration.The following description will describe the various features of the toolportion 32 when in this initial configuration. A sequential operation topermit the tool portion 32 to be reconfigured from this initialconfiguration will then be provided.

The valve sleeve 40 defines a central bore 45, and the catching sleeve41 also defines a central bore 47, wherein the bores 45, 47 correspondto each other and with a central bore 35 of the housing 34.

When in its closed position the valve sleeve 40 blocks the fluid ports20, with O-ring seals 80 positioned on opposing axial sides of the fluidports 20 to facilitate sealing. The valve sleeve 40 is axially securedrelative to the housing 34 via a number of shear screws 82 (only oneshown in the particular cross-section of FIG. 5). The valve sleeve 40includes a plurality of ports 84. As will be described in more detailbelow, to move the valve sleeve 40 towards its open position an axialactuation force is applied by the indexing sleeve 46 (not shown in FIG.5) to initially shear the screws 82 and aligned the sleeve ports 84 withthe ports 20 in the housing 34. The valve sleeve 40 includes a keymember 86 in an outer surface thereof which is received within alongitudinal key slot 88 provided in the inner surface of the housing34. Interaction between the key 86 and slot 88 prevents relativerotation between the valve sleeve 40 and the housing 34, thusmaintaining the sleeve ports 84 in the correct circumferential alignmentrelative to the ports 20 in the housing 34.

The valve sleeve 40 includes an annular recess 90 in an outer surfacethereof, extending upwardly from a downhole axial end 92 and terminatingat an annular load shoulder 93. Such a recess 90 defines an annularshroud 94 which in the illustrated configuration extends into thecentral bore 47 of the catching sleeve 41, and specifically ispositioned inside an uphole axial end 96 of the catching sleeve 41, suchthat the uphole end 96 of the catching sleeve 41 is positioned withinthe annular recess 90 of the valve sleeve 40. In this arrangement theshroud 94 physically isolates an uphole end face 98 of the catchingsleeve 41, and thus functions to prevent a passing ball, or otherobject, from engaging the uphole end face 98 which may otherwise damagethe catching sleeve 41, accidentally or prematurely cause actuation ofthe catching sleeve 41, or the like. That is, it has been recognized bythe present inventors that a passing ball may not follow a perfectlinear path through the tool 18, and in fact may continuously impact orricochet off the inner surfaces of the tool 18. If such an impact wereto occur against the end face 98 of the catching sleeve 41 then theimpact force may be sufficient to cause actuation of the catching sleeve41, and/or may cause damage to the catching sleeve 41.

The catching sleeve 41 is initially secured relative to the housing 34via a number of shear screws 100 (only one shown in FIG. 5). When inthis initial configuration the catching sleeve 41 is positioned relativeto the valve sleeve 40 such that an axial spacing or separation gap isdefined between the load shoulder 93 of the valve sleeve 40 and theuphole end face 98 of the catching sleeve 41. Such initial separationmay define a lost motion arrangement within the tool portion 32. Thatis, when axial movement of the valve sleeve 40 is initiated theseparation gap will be closed before eventual engagement between theload shoulder 93 of the valve sleeve 40 and the end face 98 of thecatching sleeve 41, wherein subsequent axial load applied by the valvesleeve 40 may shear the screws 100, and then cause axial movement of thecatching sleeve 41 towards its catching configuration, as will bedescribed in further detail below.

The uphole end 96 of the catching sleeve 41 defines an uphole tubularportion which includes a number of ports 102. These ports 102 mayfunction to permit circulation of fluid behind the catching sleeve 41,for example to facilitate circulation or removal of debris. These ports102 may also function to prevent hydraulic lock by avoiding a pressuredifferential between the interior and exterior of the valve sleeve 40.

The catching sleeve 41 includes a plurality of collet fingers 104extending longitudinally from the uphole tubular portion 96, whereineach collet finger 104 supports a seat member 106 on a distal endthereof. The collet fingers 104 are resiliently deformable, bylongitudinal bending, to permit the seat members 106 to be selectivelyradially movable relative to the central bore 47 of the catching sleeve41. Further, the collet fingers 104 define a tapering thickness alongtheir length, which functions to provide more uniform bendingtherealong, with an associated uniform stress distribution beingachieved. In the embodiment shown the fingers 104 reduce in thicknessfrom the uphole tubular portion 96 towards the seat member 106.

When the seat members 106 are positioned radially outwardly, as shown inFIG. 5, a ball may pass with minimal engagement with the seat members106. However, when the seat members 106 are positioned radiallyinwardly, as will be described in more detail below, the seat members106 collectively define a restriction within the central bore 47, andthus may be engaged by a passing ball. When the seat members 106 arepositioned radially inwardly with the catching sleeve 41 configured inits catching configuration, a ball may engage and seat against the seatmembers 106 and thus be caught within the catching sleeve 41.

The tool portion 32 further comprises an annular recess 108 which isprofiled to receive the seat members 106 when said seat members 106 arepositioned radially outwardly. In the present embodiment, the colletfingers 104 provide a bias force such that the seat members 106 arebiased radially outwardly and received within the annular recess 108,and thus positioned to permit passage of a ball. When the seat members106 are positioned radially outwardly and located within the recess 108,a circumferential gap 110 is provided between adjacent seat members 106.When the seat members 106 are moved radially inwardly, thesecircumferential gaps 110 are closed, and in some embodiments adjacentseat members 106 are engaged or are positioned in very close proximityrelative to each other, defining a substantially continuous annularstructure.

Each seat member 106 includes an uphole seat surface 112 configured tobe engaged by a ball when travelling in a downhole direction. The upholeseat surfaces 112 may be configured to provide a substantially completeor continuous engagement with a ball. Such an arrangement may facilitatesealing between a ball and the seat members 106. Such sealing may permita ball to be sealingly engaged within the catching member 41 and thussubstantially seal the central bore 47. This may allow appropriate fluiddiversion from the central bore through the fluid ports 20. Also, insome embodiments such sealing against the seat members 106 may permitcontrol of pressure uphole of the catching sleeve 41. Further, suchsealing of a ball within the catching sleeve 41 may permit the catchingsleeve 41 to be actuated, for example by a pressure differentialestablished between uphole and downhole sides of the catching sleeve 41.

In the present embodiment the uphole seat surfaces 112 are generallyconvex in shape, which provides significant advantages when engaging aball which also has a convex surface, as will be described in moredetail below.

Each seat member 106 includes a downhole seat surface 114 configured tobe engaged by a ball when travelling in an uphole direction. Such anarrangement may permit one or more balls to be engaged with the seatmembers 106 when reverse flowed through the tool, for example to permitreturn of the balls to surface, to permit reverse actuation of the tool,for example to close the valve sleeve 40. Further, such reverse flow maybe permitted or initiated to assist in clearing a blockage within thetool or associated string.

The downhole seat surfaces 114 in the embodiment shown includerespective slots 116 which permit fluid to bypass a ball when engagedagainst the downhole seat surfaces 116. Such fluid bypass may beadvantageous in an event that a ball may become trapped against thedownhole seat surfaces 114. This may be particularly advantageous inproduction wells, as production may still be achieved even in the eventof a ball becoming stuck. The slots 116 define discontinuities withinthe seat surfaces 114, such that when a ball is engaged therewith thediscontinuities may permit a degree of fluid by-pass.

The catching sleeve 41 is biased to move in an uphole direction by acoil spring 118 which acts between an annular lip 120 formed on an outersurface of the uphole tubular portion 96 of the catching sleeve 41, andan annular region 122. The coil spring 118 also functions torotationally lock the catching sleeve 41 relative to the housing 34.That is, a downhole end of the spring 118 may be rotationally securedrelative to the housing 34, and an uphole end of the spring 118 may berotationally secured relative to the catching sleeve 41. Rotationallysecuring the catching sleeve 41 relative to the housing 34 may permitthe catching sleeve 41 to be machined, for example milled, which may berequired as part of a remedial operation, for example in the event ofthe catching sleeve 41 failing to release a ball.

The tool portion 32 further comprises a release sleeve 124 which isinitially secured in the position shown in FIG. 5 via a plurality ofshear screws 126. The release sleeve 124 includes a cylindrical innersupport surface 128 which defines a region of reduced inner diameterrelative to the annular recess 108.

When the catching sleeve 41 is moved axially in a downhole direction,which will be caused by axial movement of the valve sleeve 40 towardsits open position, the seat members 106 will be displaced from theannular recess 108 and engaged with the inner support surface 128 of therelease sleeve 124, and thus deflected radially inwardly, into thecentral bore 47 and presented in a position to be engaged by a ball. Asthe seat members 106 in this position are radially supported by therelease sleeve 124, the engaged ball will become caught in the catchingsleeve 41.

The release sleeve 124 includes an annular shoulder 130 which, as willbe described in further detail below, is engaged by the seat members 106such that the catching sleeve 41 may apply an axial load in a downholedirection on the release sleeve 124.

The housing 34 defines or includes a release recess 132 which isinitially covered by the release sleeve 124. When a suitable axial loadis applied on the release sleeve 124 by the catching sleeve 41 to shearthe screws 126, the release sleeve 124 may be moved axially to uncoverthe release recess 132. When uncovered, the release recess 132 mayreceive the seat members 106, thus allowing the catching sleeve 41 to beconfigured in a release configuration.

Reference is now made to FIGS. 6A to 6D which provide perspective viewsof the catching sleeve 41 in sequential stages of manufacture. Acylindrical component 41 a, such as a metal component, is provided as inFIG. 6A, and the catching sleeve 41 is initially machined as a completecomponent to the form illustrated in FIG. 6B. As such, the catchingsleeve 41 includes the uphole tubular portion 96 with ports 102, withthe annular lip 120 for engaging the coil spring 118 (FIG. 5). In thisrespect the annular lip 120 includes circumferential gaps 140. In use atleast one gap 140 receives an axial portion of the coil spring 118 torotationally secure the catching sleeve and coil spring 118 together.

The seat members 106 are initially formed as a complete annularstructure 142, in the form that the seat members 106 adopt whenpositioned radially inwardly to catch a ball. The collet fingers 104 areprovided as longitudinal ribs which extend, at a slight inward taper,from the uphole tubular portion 96 to the complete annular structure142. The ribs define slots 105 therebetween. Once formed in this way theannular structure 142 is divided by wire cutting to form the individualseat members 106, as illustrated in FIG. 6C. Following this division,collet fingers 104 are plastically deformed radially outwardly, to theform shown in FIG. 6D, by pressing over a mandrel, for example.

However, in an alternative embodiment the catching sleeve 41 may beinstalled within the tool in the form of FIG. 6C. As such, passage of aball may cause the seat members 106 to be deflected radially outwardly,until the seat members 106 become radially supported by the releasesleeve 124, such that a ball will no longer be able to deflect the seatmembers 106 and thus will become caught in the catching sleeve 41.

Reference is now made to FIGS. 7A to 7I in which a complete operationcycle of the tool 18 of FIG. 2 will be described. In this respect, FIGS.7A to 7I provide a sequential illustration of a ball 48 driving theindexing sleeve 46 over its final discrete linear movement step toactuate the valve sleeve 40 and catching sleeve 41 to perform afracturing operation, and then subsequently permit the ball 48 to bereleased.

Referring initially to FIG. 7A the indexing sleeve 46 is positioned innon-contact relationship with the valve sleeve 40, wherein the firstarray of engagement members 52 are positioned radially inwardly inpreparation to be engaged by an approaching ball 48. Further, the valvesleeve 40 is located in its closed position to close the ports 20, andthe catching sleeve 41 is located in its free configuration such thatthe seat members 106 are positioned radially outwardly.

In FIG. 7B the ball 48 engages the first array of engagement members 52to drive the indexing sleeve 46 into engagement with the valve sleeve40, thus applying an axial load on the valve sleeve 40 and shearing thescrews 82 which initially hold the valve sleeve 40 in its closedposition. The ball 48 will continue to drive the indexing sleeve 46 andthe valve sleeve 40 until the first array of engagement members 52become aligned with a recess 40, permitting the ball 48 to progress andengage the second array of engagement members 54, which have becomedeflected radially inwardly, as illustrated in FIG. 7C. As such, theindexing sleeve 46 and valve sleeve 40 may continue to be driven throughthe housing 34 by the ball 48 until the load shoulder 93 of the valvesleeve 40 comes into engagement with the uphole axial end face 98 of thecatching sleeve 41, permitting an axial load to be applied on thecatching sleeve 41 to shear the screws 100 initially holding thecatching sleeve 41 in its free configuration.

The ball 48 may continue to drive the indexing sleeve 46 by engagementwith the second array of engagement members 54, and thus also drive thevalve sleeve 40 and the catching sleeve 41. As illustrated in FIG. 7Dthe valve sleeve 40 will eventually reach its fully open position inwhich the sleeve ports 84 become aligned with the fluid ports 20.Further, the catching sleeve 41 will eventually be configured in itscatching configuration, also shown in FIG. 7D, in that the seat members106 of the catching sleeve 41 are displaced from the correspondingrecess 108 and onto the support surface 128 of the release sleeve 124,thus deflecting the seat members 106 radially inwardly as shown in FIG.7D.

As shown in FIG. 7D, eventually the second array of engagement members54 will become aligned with an annular recess 44 within the housing 34,specifically lowermost annular recess 44 d, allowing the ball 48 to bereleased from the indexing sleeve 46 and continue in the downholedirection. In this respect it should be noted that the two lowermostannular recesses, 44 d, 44 e are provided at an axial spacing whichmatches the axial separation of the first and second arrays ofengagement members 52, 54. This permits all the engagement members 52,54 to become positioned within a recess 44 d, 44 e following the finaldiscrete linear movement step of the indexing sleeve 46, thuseffectively disabling the indexing sleeve 46. Further, when in thisposition the indexing sleeve 46 functions to lock the valve sleeve 40 inits open position.

As shown in FIG. 7E, the released ball 48 will eventually be caught bythe reconfigured seat members 106 of the catching sleeve 41, thusestablishing a blockage below the opened ports 20, functioning as adiverter to cause substantially all fluid flowing through the centralbore 35 of the tool 18 to flow radially outwardly from the ports 20 tofracture a surrounding formation, as illustrated in FIG. 1. Further, theblockage achieved by the ball 48 may permit an appropriate fluidpressure above the ball 48 to be achieved, which may be necessary toachieve appropriate fracturing of the surrounding formation.

In the specific embodiment disclosed the ports 20 become opened beforethe ball 48 lands in the catching sleeve 41, as illustrated in FIG. 7D.In such an arrangement the ball 48 will suddenly arrest or substantiallyarrest a column of fluid positioned above the ball 48 when the ball 48lands against the seat members 106 of the catching sleeve 41, as in FIG.7E. If the ports 20 are arranged to immediately provide full flow suchfast arrest of the fluid column above the ball 48 may result in initialrapid ejection of fluid through the ports 20. This may provide aninitial fluid hammer effect which could be advantageous in improvinginitial geological penetration of the ejected fluid.

However, in some situations this initial arrest of a fluid column mayprovide a significant impulse load on the catching sleeve 41 and thus onthe release sleeve 124. This initial impulse force may be of sufficientmagnitude to actuate the release sleeve 124, perhaps causing prematurerelease of the ball 48, before sufficient fracturing within thesurrounding formation has been achieved. To address this situation thepresent invention may employ a choking arrangement which functions toinitially choke the outflow of fluid through the ports 20 when initiallyopened.

In the present exemplary embodiment such a choking arrangement comprisesan erodible sleeve 150, illustrated most clearly in the enlarged view ofFIG. 7F, which is mounted on the outer surface of the housing 34 at thelocation of the ports 20. The sleeve 150, which may be formed fromaluminum, includes a plurality of orifices 152 which are aligned with arespective port 20. When flow through the ports 20 is initiated theorifices 152 function to choke the flow. However, over time the orifices152 become enlarged by erosion, which may be significant in embodimentswhere the fluid comprises a proppant material, such that the chokingeffect will decrease, until a full flow condition is established.

An enlarged view of the tool 18 in FIG. 7E in the region of the ball 48and seat members 106 of the catching sleeve 41 is provided in FIG. 7G.In the illustrated configuration the seat members 106 are engaged withthe load shoulder 130 of the release sleeve 124. Each seat member 106includes a notch 160 formed in a radially outer surface which isconfigured to permit engagement with the load profile 130 of the releasesleeve 124.

As noted above, the uphole seat surfaces 112 of the seat members 106define a convex profile. Such a convex profile permits a small region ofcontact to be achieved with the ball 48, and specifically a smallcircumferential contact region to be established. This small contactregion may permit improved control over the load path from the ball 48through the seat members 106 to be achieved. In particular, a loadvector 162 established by the engaged ball 48 may be controlled to bealigned with the notches 160 formed in the seat members 106, such thatthe load from the ball 48 may be directly transferred to the releasesleeve 124 via the load shoulder 130 of the release sleeve 124. Such anarrangement may minimize the creation of bending moments on theassociated collet fingers 104.

Furthermore, minimizing the region of contact between the ball 48 andthe seat members 106 may reduce the risk of the ball 48 becoming swagedor otherwise deformed into the seat members 106, which might otherwisecause the ball 48 to become stuck within the catching sleeve 41.

When the catching sleeve 41 is to be reconfigured to its releaseconfiguration to permit release of a caught ball 48, it is necessary todisplace the release sleeve 124 and expose the associated release recess132. In the present embodiment this is achieved by increasing thepressure on the uphole side of the ball 48 to increase the load appliedon the release sleeve 124 via the seat members 106, until the shearscrews 126 holding the release sleeve 124 in place are sheared, suchthat the pressure uphole of the ball 46 may act to drive the catchingsleeve 41 and the release sleeve 124 downwardly, as illustrated in FIG.7H. When in this configuration the spring 118 is compressed by thecatching sleeve 41, such that relieving pressure uphole of the ball 48will cause the bias force of the spring 118 to force the catching sleeve41 in an uphole direction until the seat members 106 become aligned withthe uncovered release recess 132, as shown in FIG. 7I. When aligned assuch, the collet fingers 104 will relax and thus move the seat members106 radially outwardly to be received within the release recess 132,causing the ball 48 to be released.

As described above and generally illustrated in FIG. 1, multiple tools18 according to the invention may be provided as part of a downholesystem, such as a fracturing system, wherein the tools are initiallyconfigured to be actuated upon passage of a different number of balls.The individual tools 18 may be initially configured by appropriateplacement of the associated indexing sleeves 46 relative to the housing34, and specifically relative to the indexing profile 42 of the housing34. This is exemplified in FIGS. 8A, 8B and 8C. FIG. 8A provides across-section view of the tool 18 a of FIG. 1, FIG. 8B provides across-sectional view of the immediate uphole tool 18 b of FIG. 1, andFIG. 8C provides a cross-sectional view of tool 18 c of FIG. 1.

The indexing sleeve 46 a of tool 18 a is positioned within housing 34 asuch that the indexing sleeve 46 a must be driven by one discretemovement step by passage of a single ball to actuate the associatedvalve sleeve 40 a and catching sleeve 41 a.

The indexing sleeve 46 b of tool 18 b is positioned within housing 34 bsuch that the indexing sleeve 46 b must be driven by two discretemovement steps by passage of two balls to actuate the associated valvesleeve 40 b and catching sleeve 41 b.

The indexing sleeve 46 c of tool 18 c is positioned within housing 34 csuch that the indexing sleeve 46 c must be driven by three discretemovement steps by passage of three balls to actuate the associated valvesleeve 40 c and catching sleeve 41 c.

Accordingly, an initial ball dropped through the complete system willsequentially engage the indexing sleeves 46 c, 46 b, 46 a of each tool18 c, 18 b, 18 a to move a discrete movement step, with only the valvesleeve 40 a and catching sleeve 41 a of the lowermost tool 18 a beingactuated. A second ball will move each indexing sleeve 46 c, 46 b asingle discrete movement step, with only the valve sleeve 40 b andcatching sleeve 41 b of tool 18 b being actuated. A third ball may thenactuate tool 18 c. This arrangement may be used to accommodate asignificant number of individual tools within a common system, forexample between two and fifty, and even more if necessary.

In embodiments where multiple tools 18 are used in series within acommon system it is important to ensure that the associated indexingsleeves 46 are positioned at the correct initial locations within thehousing 34. Aspects of the present invention may permit inspection ofthe location of the indexing sleeves 46 prior to deploying theassociated tools 18 into a wellbore. In this respect, an inspectionapparatus 200 in accordance with an embodiment of aspects of the presentinvention is illustrated in FIG. 9, in use with a tool 18 first shown inFIG. 2.

The inspection apparatus 200 comprises an inspection object 202 providedin the form of a ball, which is similar to a ball used to drive theindexing sleeve 46. The inspection apparatus further comprises anelongate member 204, wherein the inspection object is mounted on one endof the elongate member 204. The elongate member may be provided insections coupled together via a connector 205. The elongate member 204includes one or more markings 206. In use, the inspection object 202 isinserted into the downhole end of the tool 18 until it contacts thefirst array of engagement members 52 of the indexing sleeve 46, with theelongate member 204 extending from the tool 18. In such an arrangementthe markings 206 may provide a visible reference which permits a user toidentify or determine the position of the indexing sleeve 46.

Reference is now made to FIG. 10 in which there is shown a modifiedembodiment of the downhole tool 18 first shown in FIG. 2. In particular,FIG. 10 provides a cross-sectional view of the modified tool 18 in theregion of the actuator portion 30. In this modification the housing 34includes a plurality of housing modules 234 a, 234 b, 234 c, 234 d whichare secured together in end-to-end relation via conventional threadedconnectors to define the complete housing 34. Each housing module 234 a,234 b, 234 c, 234 d comprises a number of annular recesses 44 whichcollectively define the complete indexing profile of the tool 18. Such amodular arrangement of the tool 18 may minimize the requirement forbespoke systems, and may allow multiple specific situations to beaccommodated with a basic inventory of individual modules 234 a, 234 b,234 c, 234 d, for example containing five or ten recesses 44 each.

In the modified embodiment of FIG. 10 the two uppermost annular recesses44 f, 44 g are provided at an axial spacing which matches the axialspacing of the first and second arrays of engagement members 52, 54provided on the indexing sleeve 46. Such an arrangement may permit theindexing sleeve to become disabled prior to actuation of the tool. Forexample, as illustrated in FIG. 11, a shifting tool 240 may be deployedinto the tool to engage a shifting profile 242 on the indexing sleeve 46to pull the indexing profile in an uphole direction until the engagementmembers 52, 54 are located within a corresponding recess 44 f, 44 g.

As described above in relation to FIG. 1, individual tools 18 mayoptionally include seals 26 a, 26 b to assist to focus fracturing fluidinto the surrounding formation 14. Such seals may be provided inaccordance with flow restrictors or packers as disclosed in UK patentapplication GB1112744.6 and/or PCT application no. PCT/GB2012/051788.

An exemplary embodiment of such seal members 26 a, 26 b is illustratedin FIG. 12, in which the seal members 26 a, 26 b are mounted, forexample by slipping onto, the tool 18.

FIG. 13 shows seal 26 b in a run-in configuration (it should be notedthat seal 26 a corresponds). The seal 26 b is generally cylindrical,defining a central axis 370 and having a throughbore 380. The seal 26 bis made up from several components: a mandrel 310; a restrictor assemblyin the form of a swabbing assembly 360; and a seal backup 350, each ofthese components being arranged coaxially around the central axis 370.

The mandrel 310 is provided as a body or shaft for the seal 26 b and istapered towards one end 310 t. At an opposing end, the mandrel 310 hasan end face 310 e perpendicular to the central axis 370. A cylindricalinner surface 312 of the mandrel 10 surrounds the throughbore 80 andenables the mandrel 310 to be slotted onto another tubular (not shown)as part of a tubing string. However, in some embodiments the mandrel 310may form part of the housing 34 of the tool 18.

Towards the tapered end 310 t, an outer surface of the mandrel 310 has acylindrical annular groove 311 formed therein, for receiving an end of aset screw 313 that secures the swabbing assembly 360 to the mandrel 310.

Once the seal 26 b has been correctly assembled, it occupies therelatively compact run-in configuration shown in FIGS. 12 and 13 (orschematically in FIG. 14A).

When flow is initiated through ports 20 of the tool 18, the seal 26 b(and also 26 a) will be actuated. Initially fluid flow over the seal 26b causes a frictional drag over the swabbing assembly 360. Thefrictional effect of a sufficiently high rate of fluid flow above athreshold drags the swabbing assembly 360 outwardly in the direction offlow. Flow may then act on the underside of the swabbing assembly 360and further urge this radially outwardly until engagement with the wallof the borehole 12, as shown in FIG. 14B. By arranging the seals 26 a,26 b facing each other, the flow from the ports 20 of the tool 18 mayact to actuate both seals 26 a, 26 b.

Reference is now made to FIGS. 15A to 15D in which there is shown a toolportion 432 of a downhole tool 418 having a coupling arrangementaccording to an embodiment of the present invention.

The downhole tool 418 and tool portion 432 are similar to the downholetool 18 and tool portion 32 described above and like features of thedownhole tool 418 and tool portion 432 are represented by like numeralsincremented by 400.

The downhole tool portion 432 comprises a housing 434 having a number oflateral fluid ports 420 (two lateral fluid ports 420 are shown), a valvesleeve 440 slidably disposed within the housing 434 and also having anumber of lateral fluid ports 484 (two lateral fluid ports 484 areshown), a catching sleeve 441 slidably disposed within the housing 434and a coupling arrangement C.

In use, the valve sleeve 440 is actuatable between a closedconfiguration in which fluid flow through the ports 420, 484 isprevented and an open configuration in which fluid flow is permittedwhile the catching sleeve 441 is actuatable by the valve sleeve 440between a free configuration (as shown in FIG. 15A) and a catchingconfiguration (as shown in FIG. 15B) suitable for catching an objectsuch as a ball. Rotational movement of the valve sleeve 440 istransmitted to the catching sleeve 441 and the housing 434 via thecoupling arrangement C and provides a rotational lock and/or ensuresrotational alignment of the valve sleeve 440, catching sleeve 441 andhousing 434 while also permitting relative axial movement between thevalve sleeve 440, the catching sleeve 441 and the housing 434.

The coupling arrangement C in the illustrated embodiment comprisesradially extending keys 486 disposed in recesses 485 provided in astepped outer surface portion 489 of the valve sleeve 441, the keys 486extending radially from the valve sleeve 441 and through correspondingslots 487 in the catching sleeve 441 and into a plurality of recesses488 provided in an inner wall surface of the housing 434.

In use, the coupling arrangement C provides a rotary coupling betweenthe valve sleeve 440, the catching sleeve 441 and the housing 434 sincethe interaction between the keys 486, slots 487 and recesses 488prevents relative rotation between the valve sleeve 440, the catchingsleeve 441 and the housing 434, maintaining the sleeve ports 484 in thecorrect circumferential alignment relative to the ports 420 in thehousing 434. Since the keys 486 can translate axially in the slots 487of the catching sleeve 441 and the recesses 488 of the housing 434,relative axial movement of the valve sleeve 440 and the catching sleeve441 relative to the housing 434 is permitted, the maximum stroke orlength of axial travel permitted substantially defined by the length ofthe housing recesses 488.

The tool portion 432 is illustrated in an initial configuration in FIG.15A, with the valve sleeve 440 in a closed position and the catchingsleeve 441 in a free configuration. In this position, the valve sleeve440 is initially axially secured relative to the housing 434 via anumber of shear screws 482 (one screw 482 is shown). The keys 486 aredisposed at the upper end of the housing recesses 488 and at a positionintermediate the ends of the slots 487 of the catching sleeve 441.

In order to move the valve sleeve 440 towards its open position, that isfrom the position shown in FIG. 15A to the position shown in FIG. 15B,an axial actuation force is applied to the valve sleeve 440 by anindexing sleeve 446 to shear the screws 482 and substantially align thesleeve ports 484 with the ports 420 in the housing 434 in a similarmanner to that described above.

As can be seen from FIGS. 15A to 15D, the slots 487 of the catchingsleeve 441 and the recesses 488 of the housing 434 partially axiallyoverlap, such that axial movement of the valve sleeve 441 does notimmediately result in axial movement of the catching sleeve 441 from thefree configuration shown in FIG. 15A to the catching configuration shownin FIG. 15B; axial movement of the valve sleeve 440 and catching sleeve441 occurring when the keys 486 impinge on the lower end of the slots487 of the catching sleeve 441.

It is noted that in the position shown in FIG. 15B, the catching sleeve441 has been moved to its catching configuration but the ports 420, 484are not fully aligned and the keys 486 are not yet in abutment with thelower end of the housing recesses 488.

As with the catching sleeve 41 described above, the catching sleeve 441includes a plurality of longitudinally extending collet fingers 404,wherein each collet finger 404 supports a seat member 406 on a distalend thereof. When the seat members 406 are positioned radiallyoutwardly, as shown in FIG. 15A, an object such as a ball may passwithout any contact or with minimal engagement with the seat members406. However, when the catching sleeve 441 is moved axially in adownhole direction, which will be caused by axial movement of the valvesleeve 440 towards its open position (to the right as shown in thefigures), the seat members 406 will be displaced from an annular recess408 in the housing 434 and engaged with a release sleeve 424, and thusdeflected radially inwardly, and presented in a position to be engagedby a ball. Thus, when the seat members 406 are positioned radiallyinwardly with the catching sleeve 441 configured in its catchingconfiguration as shown in FIG. 15B, a ball may engage and seat againstthe seat members 406 and thus be caught within the catching sleeve 441.

Each seat member 406 includes an uphole seat surface 412 configured tobe engaged by a ball when travelling in a downhole direction. The upholeseat surfaces 412 may be configured to provide a substantially completeor continuous engagement with a ball, permitting a ball to be sealinglyengaged within the catching member 441. Such sealing of a ball withinthe catching sleeve 441 permits the catching sleeve 441 to be actuated,for example by a pressure differential established between uphole anddownhole sides of the catching sleeve 441, to move the tool 418 from theposition shown in FIG. 15B to the position shown in FIG. 15C

In the position shown in FIG. 15C, the keys 486 abut the lower end ofthe housing recesses 488 and the ports 420 are now fully open. By virtueof the coupling arrangement C, the catching sleeve 441 is free to moveaxially relative to the valve sleeve 440 under the influence of thepressure differential created across the ball to actuate the releasesleeve 424 of the downhole tool 418 without disturbing the condition ofthe ports 420.

The housing 434 defines or includes a release recess 432 which isinitially covered by the release sleeve 424. However, when a suitableaxial load is applied on the release sleeve 424 by the catching sleeve441, the release sleeve 424 is moved axially to uncover the releaserecess 432, as shown in FIG. 15C. In the position shown in FIG. 15C, thekeys 486 abut the lower end of the slots 487 and the housing recesses488.

With reference in particular to FIGS. 15B and 15C, it can be seen thatmovement of the tool 418 from the position shown in FIG. 15B to theposition shown in FIG. 15C compresses a coil spring 418 interposedbetween the catching sleeve 441 and the housing 434. The coil spring 418is biased to move the catching sleeve 441 in an uphole direction (to theleft as shown in the figures) and under the influence of the coil spring418 the catching sleeve 441 moves from the position shown in FIG. 15C tothe position shown in FIG. 15D, such that the seat members 408 arereceived in the uncovered release recess 432. In this position, thecatching sleeve 441 is configured in a release configuration whichpermits the ball to be released.

Reference is now made to FIGS. 16A to 16E in which there is shown a toolportion 532 of a downhole tool 518 having a coupling arrangement C′according to another embodiment of the present invention. In thisembodiment, the tool 518 provides a positive indication at surface thatan activation event, for example opening of ports 520, has occurred.

The downhole tool 518 and tool portion 532 are similar to the downholetools 18, 418 and tool portions 32, 432 described above and likefeatures of the downhole tool 518 and tool portion 532 are representedby like numerals incremented by 500.

As shown in FIG. 16A, the downhole tool portion 532 comprises a housing534 having a number of lateral fluid ports 520 (two lateral fluid ports520 are shown), a valve sleeve 540 slidably disposed within the housing534 and also having a number of lateral fluid ports 584 (two lateralfluid ports 584 are shown), a catching sleeve 541 slidably disposedwithin the housing 534 and a coupling arrangement C′.

As in the coupling arrangement C, the coupling arrangement C′ provides arotary coupling between the valve sleeve 540, the catching sleeve 541and the housing 534 by virtue of the interaction between keys 586, slots587 and recesses 588 while permitting relative axial movement of thevalve sleeve 540 and the catching sleeve 541 relative to the housing534.

The tool portion 532 is illustrated in an initial configuration in FIG.16A, with valve sleeve 540 in a closed position and catching sleeve 541in a free configuration.

In this position, the valve sleeve 540 is initially axially securedrelative to housing 534 via a number of shear screws 582 (one screw 582is shown) and the keys 586 are disposed adjacent an upper end of thehousing recesses 588 and at a position adjacent to the lower end of theslots 587 of the catching sleeve 541.

In order to move the catching sleeve 541 from its free configurationshown in FIG. 16A to its catching configuration shown in FIG. 16B, anaxial actuation force is applied to the valve sleeve 540 by an indexingsleeve 546 to shear the screws 582, permitting the valve sleeve 540 tomove in a downhole direction (to the right as shown in the figures). Inthis embodiment, when the catching sleeve 541 is moved by the valvesleeve 540 from the position shown in FIG. 16A to the position shown inFIG. 16B, the valve sleeve 540 is not moved to a fully openconfiguration but to an intermediate position in which the ports 520 arestill closed (ports 584 and 520 are not aligned).

As with the catching sleeve 441 described above, the catching sleeve 541includes a plurality of longitudinally extending collet fingers 504,wherein each collet finger 504 supports a seat member 506 on a distalend thereof. When the seat members 506 are positioned radiallyoutwardly, as shown in FIG. 16A, an object such as a ball may passwithout any contact or with minimal engagement with the seat members506. However, when the catching sleeve 541 is moved axially in adownhole direction, which will be caused by axial movement of the valvesleeve 540 (to the right as shown in the figures), the seat members 506will be displaced from an annular recess 508 in the housing 534 andengaged with a release sleeve 524, and thus deflected radially inwardly,and presented in a position to be engaged by a ball. Thus, when the seatmembers 506 are positioned radially inwardly with the catching sleeve541 configured in its catching configuration as shown in FIG. 16B, aball may engage and seat against the seat members 506 and thus be caughtwithin the catching sleeve 541.

Each seat member 506 includes an uphole seat surface 512 configured tobe engaged by a ball when travelling in a downhole direction. The upholeseat surfaces 512 may be configured to provide a substantially completeor continuous engagement with a ball, permitting a ball to be sealinglyengaged within the catching member 541. Such sealing of a ball withinthe catching sleeve 541 permits the catching sleeve 541 to be actuated,for example by a pressure differential established between uphole anddownhole sides of the catching sleeve 541, to move the tool 518 from theposition shown in FIG. 16B to the position shown in FIG. 16C.

In the position shown in FIG. 16C, the keys 586 are at an intermediateposition in the housing recesses 588 and the ports 520 remain closed. Byvirtue of the coupling arrangement C′, the catching sleeve 541 is freeto move axially relative to the valve sleeve 540 under the influence ofthe pressure differential created across the ball to actuate the releasesleeve 524 of the downhole tool 518 without disturbing the condition ofthe ports 520.

The housing 534 defines or includes a release recess 532 which isinitially covered by the release sleeve 524. However, when a suitableaxial load is applied on the release sleeve 524 by the catching sleeve541, the release sleeve 524 is moved axially to uncover the releaserecess 532, from the position shown in FIG. 16C to the position shown inFIG. 16D. In this position, the keys 586 abut the upper end of the slots587 and are disposed adjacent the lower end of the recesses 588.

As in previous embodiments, movement of the tool 518 from the positionshown in FIG. 16C to the position shown in FIG. 16D compresses a coilspring 518 interposed between the catching sleeve 441 and the housing434. The coil spring 518 is biased to move the catching sleeve 541 in anuphole direction (to the left as shown in the figures) and under theinfluence of the coil spring 518 the catching sleeve 541 moves from theposition shown in FIG. 16D to the position shown in FIG. 15E, such thatthe seat members 508 of the catching sleeve 541 are received in theuncovered release recess 532. In this position, the catching sleeve 541is configured in a release configuration which permits the ball to bereleased and the valve sleeve 541 has been moved to the openconfiguration (ports 520 and 584 are fully aligned). With the ports 520open, a pressure drop detectable at surface provides a positiveindication that the ports 520 have been opened correctly. In thisposition, the keys 586 are disposed adjacent the bottom of the recesses588 and the slots 587.

As in other embodiments, the tools 418, 518 may further include anoptional choke 450, 550, the choke 450, 550 associated with the fluidport 420, 520 to choke flow through the fluid port 420, 520 once openedas described above.

In the various embodiments described above, downhole tools are providedwith a catching arrangement which is operated to move between free andcatching configurations by an associated valve member. However, in otherembodiments such a catching arrangement may be operated independently ofa valve member. Such an arrangement is illustrated in FIG. 17A,reference to which is now made. The embodiment shown in FIG. 17A issimilar in many respects to the embodiment first shown in FIG. 2, and assuch like features share like reference numerals, incremented by 700.

The downhole tool, generally identified by reference numeral 718,includes a tool housing 734 which includes a plurality of ports 720through a wall thereof. The tool 718 includes a valve sleeve 740 whichincludes a plurality of ports 784, wherein the sleeve 740 is illustratedin FIG. 17A in a closed position, such that the ports 720 in the housing734 are initially closed.

The housing 734 defines first and second indexing profiles 742 a, 742 b,which each include a plurality of annular recesses 744. A first indexingsleeve 746 a is arranged within the housing 734 relative to the firstindexing profile 742 a and uphole of the valve sleeve 740. As will bedescribed in more detail below, the first indexing sleeve 746 a isconfigured to operate the valve sleeve 740 to be moved to an openposition following the passage of a predetermined number of balls 748.

The tool 718 further includes a catching sleeve 741, which includes aplurality of fingers 804 and associated seat member 806, wherein thecatching sleeve 741 is arranged adjacent a release sleeve 824, in asimilar manner as defined above. In the arrangement shown in FIG. 17A,the catching sleeve 741 is positioned within a free configuration, suchthat any balls are free to pass therethrough, wherein the catchingsleeve 741 is capable of being reconfigured into a catchingconfiguration in which any passing balls may become caught. The preciseform and operation of the catching sleeve 741 is similar to thatdescribed in connection with other embodiments, and as such no furtherdetailed description will be given.

A second indexing sleeve 746 b is arranged within the housing 734relative to the second indexing profile 742 b and uphole of the catchingsleeve 741. As will be described in more detail below, the secondindexing sleeve 746 b is configured to operate the catching sleeve 741to move to its catching configuration following the passage of a numberof balls 748.

In the arrangement shown in FIG. 17A, each indexing sleeve 746 a, 746 bis initially arranged to be moved in the same number of discretemovement steps before reaching an actuation site. Thus, as illustratedin FIG. 17B, when a predetermined number of balls 748 have passed, thefirst indexing sleeve 746 a will have moved to actuate and move thevalve sleeve 740 to open the fluid ports 720, and the second indexingsleeve 746 b will have moved to actuate and move the catching sleeve 741to radially collapse the seat members 806 to permit the ball 748 tobecome caught. The ball 748 may then function to block the central bore735 of the tool 718, allowing substantially all flow to be divertedthrough the open ports 720.

Reference is now made to FIGS. 18A and 18B which show different stagesof operation of a downhole tool, generally identified by referencenumeral 818, in accordance with an alternative embodiment of the presentinvention. Tool 818 is similar in many respects to tool 18 shown in FIG.2, and as such like features share like reference numerals.

Tool 818 includes a housing 834 which includes first, second and thirdsets of ports 820 a, 820 b, 820 c through a wall thereof. The tool 818includes first, second and third valve sleeves 740 each arranged withinthe housing 834, and each positioned relative to a respective set ofports 820 a, 820 b, 820 c, wherein the sleeves 840 a, 840 b, 840 c areillustrated in FIG. 18A in a closed position, such that the ports 820 a,820 b, 820 c in the housing 834 are initially closed.

The housing 834 defines first, second and third indexing profiles 842 a,842 b, 842 c which each include a plurality of annular recesses 844. Afirst indexing sleeve 846 a is arranged within the housing 834 relativeto the first indexing profile 842 a and uphole of the first valve sleeve840 a. A second indexing sleeve 846 b is arranged within the housing 834relative to the second indexing profile 842 b and uphole of the secondvalve sleeve 840 b. Similarly, a third valve sleeve 840 c is arrangedwithin the housing 834 relative to the third indexing profile 842 c anduphole of the third valve sleeve 840 b. As will be described in moredetail below, the indexing sleeves 846 a, 846 b, 846 c are eachconfigured to operate the respective valve sleeve 840 a, 840 b, 840 c tobe moved to an open position following the passage of a predeterminednumber of balls 848.

The tool 818 includes a single catching sleeve 841 located downhole ofthe third valve sleeve 840 c, wherein the catching sleeve 841 includes aplurality of fingers 904 and associated seat members 906, and isarranged adjacent a release sleeve 924, in a similar manner as definedabove. In the arrangement shown in FIG. 18A, the catching sleeve 841 ispositioned within a free configuration, such that any balls are free topass therethrough, wherein the catching sleeve 841 is capable of beingreconfigured into a catching configuration in which any passing ballsmay become caught. The precise form and operation of the catching sleeve841 is similar to that described in connection with other embodiments,and as such no further detailed description will be given.

In use, each passing ball 848 will cause each indexing sleeve 846 a, 846b, 846 c to progress in discrete steps of movement towards theirassociated valve sleeves 840 a, 840 b, 840 c. When a predeterminednumber of objects have passed the valve sleeves 840 a, 840 b, 840 c willbe actuated to move towards their open positions to open the respectiveports 820 a, 820 b, 820 c, as illustrated in FIG. 18B. Further,actuation of the third valve sleeve 840 c will cause the catching sleeve841 to become configured into its catching configuration, such that apassing object 848 becomes caught. In such an arrangement the centralbore 835 may become blocked, such that substantially all flow isdiverted through the open ports 820 a, 820 b, 820 c.

Although the embodiment shown in FIG. 18A has three valve members, itwill be appreciated that any number may be used, for example two ormore.

In the embodiments described above the present invention provides foractuation of either a valve sleeve and/or a catching sleeve. However, itwill be appreciated that in alternative embodiments features of thepresent invention may be utilized to operate any type of downhole tool,in any downhole operation and in any required sequence. An example ofone such alternative embodiment is schematically illustrated in FIGS.19A to 19D, which show the sequential operation of a downhole system,generally identified by reference numeral 900.

Referring initially to FIG. 19A, the downhole system 900 includes atubing string 901 which is shown positioned within a wellbore 902. Thetubing string 901 includes a number of tools and tool components alongits length.

More specifically, the tubing string 901 includes first, second andthird axially arranged packers 910 a, 910 b, 910 c. Each packer 910 a,910 b, 910 c includes an associated actuator, which each includes anindexing sleeve 912 a, 912 b, 912 c. The indexing sleeves 912 a, 912 b,912 c are provided in a similar form to indexing sleeve 46 first shownin FIG. 2, and as such no further detailed description will be given.Each indexing sleeve 912 a, 912 b, 912 c is arranged within the tubingstring 901 to cooperate with respective indexing profiles (notillustrated) on the inner surface of the tubing string 901, to be movedin a number of discrete steps of movement towards an actuation site uponpassage of a corresponding number of objects, such as balls. Uponreaching the respective actuation sites, the indexing sleeves 912 a, 912b, 912 c actuate the respective packers 910 a, 910 b, 910 c, as will bedescribed in more detail below.

A first valve assembly 932 a is positioned between the first and secondpackers 910 a, 910 b, and a second valve assembly 932 b is positionedbetween the second and third packers 910 b, 910 c. Each valve assembly932 a, 932 b is configured in the same manner as tool portion 32 firstshown in FIG. 2, and as such no further detailed description will begiven. Thus, each valve assembly 932 a, 932 b includes a valve member940 a, 940 b initially arranged in FIG. 19A to block fluid ports 920 a,920 b through a wall of the tubing string 901. Further, each valveassembly 932 a, 932 b includes a catching sleeve 941 a, 941 b which isconfigurable from a free configuration in which an object may freelypass therethrough, to a catching configuration in which an object may becaught.

Each valve assembly 932 a, 932 b includes an associated actuator, whicheach includes an indexing sleeve 946 a, 946 b. The indexing sleeves 946a, 946 b are provided in a similar form to indexing sleeve 46 firstshown in FIG. 2, and as such no further detailed description will begiven. Each indexing sleeve 946 a, 946 b is arranged within the tubingstring 901 to cooperate with respective indexing profiles (notillustrated) on the inner surface of the tubing string 901, to be movedin a number of discrete steps of movement towards an actuation site uponpassage of a corresponding number of objects, such as balls. Uponreaching the respective actuation sites, the indexing sleeves 946 a, 946b actuate the respective valve assemblies 932 a, 932 b to move the valvemembers 940 a, 940 b to open the respective ports 920 a, 920 b, and toreconfigure the respective catching sleeves 941 a, 941 b to theircatching configurations.

In a similar manner to the embodiments described above, the requirednumber of passing objects to cause the various indexing sleeves 912 a,912 b, 912 c, 946 a, 946 b to reach their respective actuation sites isdetermined by the initial positioning of said indexing sleeves. In thisrespect, a significant advantage of the present invention is the abilityto provide an operator with significant flexibility in terms of settingany desired sequence of operation of downhole tools. However, in thepresent exemplary embodiments, the various indexing sleeves 912 a, 912b, 912 c, 946 a, 946 b are initially arranged such that the packers 910a, 910 b are caused to be set upon passage of a first object, the secondvalve assembly 932 b is actuated upon passage of a second object, andthe first valve assembly 932 a is actuated upon passage of a thirdobject. Such operation will now be described with reference to FIGS.19B, 19C and 19D.

Referring first to FIG. 19B, a first object, specifically a first ball948 a is passed along the tubing string 901, moving each indexing sleeve912 a, 912 b, 912 c, 946 a, 946 b a single discrete step. This singlediscrete step is sufficient to cause the indexing sleeves 912 a, 912 b,912 c to actuate the respective packers 910 a, 910 b, 910 c, toestablish sealing engagement with a wall 903 of the wellbore 903 andachieve zonal isolation. The indexing sleeves 912 a, 912 b, 912 c mayprovide any suitable actuation of the packers 910 a, 910 b, 910 c. Forexample, the indexing sleeves 912 a, 912 b, 912 c may axially compressthe respective packers 910 a, 910 b, 910 c. Alternatively, the indexingsleeves 912 a, 912 b, 912 c may establish fluid communication with asource of hydraulic power which may be used to actuate the packers 910a, 910 b, 910 c. For example, the indexing sleeves 912 a, 912 b, 912 cmay open one or more ports which provide fluid communication withhydrostatic pressure within the annulus 904 between the tubing string901 and the wall 903 of the wellbore 902.

Upon passage of a second ball 948 b, as shown in FIG. 19C, indexingsleeves 946 a, 946 b are each caused to move a further single discretestep. Such movement is sufficient to cause indexing sleeve 946 b todrive the valve member 940 b of the second valve assembly 932 b to openthe ports 920 b, and also reconfigure the catching sleeve 941 b so thatthe ball 948 b may become caught. In such a configuration a fluid, suchas a fracturing fluid, flowing along the tubing string 901 may bediverted outwardly through the opened ports 920 b to treat a surroundingformation in the zone defined between the second and third packers 910b, 910 c. In a similar manner to that described above in otherembodiments, the catching sleeve 941 b may eventually be configured torelease the ball 948 b, again allowing full bore access along the tubingstring 901.

Upon passage of a third ball 948 c, as shown in FIG. 19D, indexingsleeve 946 a is caused to move a further single discrete step, to nowengage and drive the valve member 940 a of the first valve assembly 932a to open the ports 920 a, and also reconfigure the catching sleeve 941a so that the ball 948 c may become caught. In such a configuration afluid, such as a fracturing fluid, flowing along the tubing string 901may be diverted outwardly through the opened ports 920 c to treat asurrounding formation in the zone defined between the first and secondpackers 910 a, 910 b. In a similar manner to that described above inother embodiments, the catching sleeve 941 c may eventually beconfigured to release the ball 948 c, again allowing full bore accessalong the tubing string 901.

As noted above, the present invention can permit downhole tools to beactuated in any desired sequence. In the system 900 of FIG. 19A, theindexing sleeves 912 a, 912 b, 912 c are initially arranged to set theassociated packers 910 a, 910 b, 910 c upon passage of a singleactuation object. However, in a modified embodiment indexing sleeve 912c may be arranged to set packer 910 c upon passage of a first object,indexing sleeve 912 b may be arranged to set packer 910 b upon passageof a second object, and indexing sleeve 912 a may be arranged to setpacker 910 a upon passage of a third object. In such an arrangement apassing object may only be required to actuate a single packer. This mayprovide advantages, in terms of maximizing the available energy of anobject for actuating a single packer, rather than requiring the objectto have sufficient energy to actuate a number of downhole tools. In suchan arrangement there might be the possibility that the availableactuation energy of an object is dissipated before all target tools orpackers are actuated.

Reference is now made to FIG. 20A in which there is shown a downholesystem, generally identified by reference numeral 1000, in accordancewith an embodiment of the present invention. The downhole system 1000includes a tubing string 1001 which is shown positioned within awellbore 1002. The tubing string 1001 includes a number of tools andtool components along its length.

More specifically, the tubing string 901 includes first and second valveassemblies 1032 a, 1032 b, wherein each valve assembly 1032 a, 1032 b isconfigured in the same manner as tool portion 32 first shown in FIG. 2,and as such no further detailed description will be given. Thus, eachvalve assembly 1032 a, 1032 b includes a valve member 1040 a, 1040 binitially arranged in FIG. 20A to block fluid ports 1020 a, 1020 bthrough a wall of the tubing string 1001. Further, each valve assembly1032 a, 1032 b includes a catching sleeve 1041 a, 1041 b which isconfigurable from a free configuration in which an object may freelypass therethrough, to a catching configuration in which an object may becaught.

Each valve assembly 1032 a, 1032 b includes an associated actuator,which each includes an indexing sleeve 1046 a, 1046 b. The indexingsleeves 1046 a, 1046 b are provided in a similar form to indexing sleeve46 first shown in FIG. 2, and as such no further detailed descriptionwill be given. Each indexing sleeve 1046 a, 1046 b is arranged withinthe tubing string 1001 to cooperate with respective indexing profiles(not illustrated) on the inner surface of the tubing string 1001, to bemoved in a number of discrete steps of movement towards an actuationsite upon passage of a corresponding number of objects, such as balls.Upon reaching the respective actuation sites, the indexing sleeves 1046a, 1046 b actuate the respective valve assemblies 1032 a, 1032 b to movethe valve members 1040 a, 1040 b to open the respective ports 1020 a,1020 b, and to reconfigure the respective catching sleeves 1041 a, 1041b to their catching configurations.

In a similar manner to the embodiments described above, the requirednumber of passing objects to cause the indexing sleeves 1046 a, 1046 bto reach their respective actuation sites is determined by the initialpositioning of said indexing sleeves.

A conduit 1004 runs alongside the tubing string 1001. The conduit may beof any suitable form and provide any required function. For example, theconduit 1004 may be configured to provide fluid, electrical, opticalcommunication or the like along the tubing string 1001.

In the present embodiment illustrated, the conduit 1004 extends alongthe outer surface of tubing string 1001 at a circumferential locationwhich is absent from any fluid ports, as illustrated in FIG. 20B, whichis a sectional view of the system 1000 of FIG. 20A, taken through lineB-B. In this respect, the ports 1020 a are evenly circumferentiallydistributed around the tubing string 1001, with the exception that aport is absent from the circumferential region (the 12 o'clock positionin the illustrated embodiment) at which the conduit 1004 is located.Accordingly, the conduit 1004 may be protected from direct exposure toany fluids, such as a fracturing fluid, exiting the ports 1020 a.

It should be understood that the embodiments described herein are merelyexemplary and that various modifications may be made thereto withoutdeparting from the scope of the invention.

What is claimed is:
 1. A downhole tool, comprising: a housing defining acentral bore and including a fluid port; a valve member mounted withinthe housing and being movable from a closed position in which the fluidport is blocked to an open position in which the fluid port is opened; acatching arrangement mounted within the housing and comprising one ormore radially movable seat members, and being configurable from a freeconfiguration in which the seat members permit an object to pass throughthe tool, to a catching configuration in which the seat members catch anobject passing through the tool; and a variable choke arrangementoperable to choke fluid flow through the fluid port.
 2. The downholetool according to claim 1, wherein the variable choke arrangementprovides a decreasing degree of choking to a flow through the fluid portonce opened.
 3. The downhole tool according to claim 2, wherein thedecreasing degree of choking permits the pressure within the tool to begradually reduced following opening of the fluid port.
 4. The downholetool according to claim 1, wherein the variable choke arrangementpermits monitoring of the downhole tool.
 5. The downhole tool accordingto claim 1, wherein the choke arrangement comprises a dissipating memberassociated with the fluid port, said dissipating member being arrangedto dissipate in response to flow through the fluid port.
 6. The downholetool according to claim 5, wherein the dissipating member defines anorifice, wherein said orifice is enlarged in response to flow throughthe fluid port.
 7. The downhole tool according to any preceding claim,wherein the variable choke arrangement is mounted on the housing.
 8. Thedownhole tool according to claim 1, wherein the variable chokearrangement is operable to prevent premature release of an object fromthe catching arrangement.
 9. The downhole tool according to claim 1,wherein the downhole tool comprises a release arrangement.
 10. Thedownhole tool according to claim 9, wherein the release arrangementcomprises a release member.
 11. The downhole tool according to claim 10,wherein the release member is mounted within the housing.
 12. Thedownhole tool according to any of claims 10, wherein the release memberis axially movable by the catching arrangement between a supportingposition in which the release member permits the catching arrangement tobe configured in its catching configuration by radially supporting theseat member in a radially inward or retracted position, towards ade-supporting position in which the release member permits the catchingarrangement to be configured in a release configuration by removing theradial support to the seat members, allowing the seat members to bemoved radially outwardly to permit release of a previously caughtobject.
 13. The downhole tool according to claim 9, wherein the releasearrangement is actuated by axial movement of the catching arrangement.14. The downhole tool according to claim 9, wherein the releasearrangement is actuated by establishing a pressure condition in thedownhole tool.
 15. The downhole tool according to claim 9, wherein thechoking arrangement functions to prevent premature actuation of therelease arrangement.
 16. The downhole tool according to claim 10,wherein the housing defines a release recess and the release membercovers this release recess when said release member is located withinits supporting position, and the release member is movable within thehousing towards its de-supporting position to uncover the release recessand thus permit the seat members to be moved radially outwardly andreceived within the release recess to permit release of an object. 17.The downhole tool according to claim 10, wherein the release memberdefines a load profile, and the catching arrangement defines a loadprofile configured to engage a load profile on the release member topermit the catching arrangement to apply a force on the release memberto move the release member towards its de-supporting position.
 18. Thedownhole tool according to claim 10, wherein at least one seat membercomprises a load profile configured to engage a load profile on therelease member to permit the release member to be moved by the catchingarrangement.
 19. The downhole tool according to claim 10, wherein thecatching arrangement is biased in a direction opposite to the directionin which the release member is moved to be positioned within itsde-supporting position.
 20. A method for delivering a fluid into awellbore, comprising: arranging a downhole tool within a wellbore,wherein the tool comprises: a tool housing defining a central bore and afluid port; a valve member mounted within the housing and initiallyarranged to at least partially block the fluid port; a catchingarrangement mounted within the housing and comprising one or moreradially movable seat members, wherein the catching arrangement isinitially configured in a free configuration in which the seat memberspermit an object to pass through the tool; and a variable chokearrangement operable to choke fluid flow through the fluid port;actuating the valve member to move to open the fluid port; reconfiguringthe catching arrangement from its free configuration to a catchingconfiguration in which the seat members can catch an object passingthrough the tool; delivering a fluid through the central bore andoutwardly through the open fluid port; and variably choking flow throughthe fluid port using the variable choke arrangement.